The best part of the iTunes App Store is that you don’t need to spend a single cent to fill your iPhone with amazing applications. There are tons of developers dishing out quality free applications daily.

So in honor of cheapskates everywhere, this article features 100 free and useful iPhone apps. The apps are organized into ten categories: Social, Business, Productivity, Financial, Utilities, Mobile & Remote File Access, News & Weather, Travel, Food, and Audio & Video.

A few of these are free for a limited time only so be sure to act fast!

Do you use a Mac or iPad? Be sure to also check out our roundups of 100 Incredibly Useful & Free Mac Apps, 100 Incredibly Useful & Free iPad Apps and the all-new The Top 100 iPad Apps!

Social

Twitter – Discover what’s happening right now, anywhere in the world with the official Twitter for iPhone app. Realtime search, Top Tweets, trending topics and maps show whats happening now everywhere and nearby. Tweet, send DMs, share photos, videos and links to your friends and the world. Don’t have an account? Just sign up from the app!

Facebook – Facebook for iPhone makes it easy to stay connected and share information with friends. Use your iPhone to start a conversation with Facebook Chat, check your friends’ latest photos and status updates, look up a phone number, or upload your own mobile photos to Facebook while on the go.

Skype – With Skype on your iPhone or iPod touch you can call and instant message anyone else on Skype for free. You can also call landlines and mobiles and send SMS anywhere in the world, at great rates. Skype is free to download and easy to use.

Bump – Bump makes sharing with people quick and easy. Just pick what you want to send, then hold your phones and gently bump hands with another person using Bump. Share photos and contacts, compare friends, or become Facebook friends in seconds!

AIM (Free Edition) – Chat with your Facebook friends on AIM for iPhone, even if they’re not AIM users. To get started, just click Facebook Connect button at the top of the AIM Buddy List. Your Facebook friends and groups will be added to your Buddy List (with the Facebook icon next to their name). Now chatting with your Facebook friends is as easy as using AIM.

Foursquare – Foursquare helps you find new ways to explore your city. See where your friends are, learn about the places they frequent and unlock rewards as you travel through the city.

Friends Around Me – Friends Around Me is a free mobile app for interacting with friends 24/7 across social networks: check-in directly to Foursquare and share status on Twitter, Facebook. Meet new people nearby or across the world through an interactive location-based search.

LinkedIn – LinkedIn for iPhone puts your professional network just a touch away. Walk into any interview or client meeting with the ability to look up the details and connect with over 60 million professionals worldwide. Get the latest updates and messages from your network and keep them up-to-date with your status in real-time.

Messagey – ‘Messagey!’ is the ultimate free SMS app with super-fast load times and super-fast message sending, allowing you to send your messages, super-fast! It’s quick and convenient, since it brings an all new way of sending messages to the iPhone, with the introduction of our intuitive ‘Message Sliders’, allowing you to save commonly used messages – so they’re ready to send with just a few taps.

Fring – Fring is a multi-award winning mobile application that lets you make free voice calls, free video calls (one way) and live IM chats directly from your iPhone and iPod touch.

Business

Dragon Dictation – Dragon Dictation is an easy-to-use voice recognition application powered by Dragon NaturallySpeaking that allows you to easily speak and instantly see your text or email messages. In fact, it’s up to five (5) times faster than typing on the keyboard. With Dragon Dictation you can also update your Facebook status, send notes and reminders to yourself, or Tweet to the world….all using your voice. So when you’re on-the-go, stop typing and start speaking – from short text messages to longer email messages, and anything in between.

Currency Converter – Convert exchange rates for over 180 currencies and 4 metals. Type conversion amounts using a custom big-button keypad.

Jobs – The CareerBuilder.com iPhone application offers a unique and powerful way to search nearly 2 million jobs on CareerBuilder.com, the US’s largest job site.

Cisco WebEx Meeting Center – Tap into WebEx online meetings on your iPhone, wherever you are! Use this application to attend, schedule, and start meetings. Get the full meeting experience with native 3G or WiFi support for simultaneous data and audio. Don’t just listen in, join in!

MailChimp – With the MailChimp iPhone app you can: Add subscribers to your mailing list, View fancy reports for your email campaigns, See how your campaigns are spreading on Twitter, See where in the world your subscribers are, Edit and unsubscribe people from your lists, View Chimp Chatter—a newsfeed that shows the status of your account, and Refer friends to MailChimp and earn free credits.

Concur Mobile – With Concur Mobile, Concur clients can manage their travel itineraries and expense transactions from their smartphone – giving travelers the freedom of mobility and ease of use wherever their travels take them.

UPS Mobile – UPS Mobile App for iPhone is specially designed with features that let you easily manage your shipments on the go. This App lets you track and nickname shipments, create shipping labels, find UPS service locations via GPS, and estimate shipment costs and delivery times.

FedEx Mobile – FedEx Mobile for iPhone provides up-to-date shipment tracking information. Simply input your FedEx tracking number and you can quickly retrieve the status of your shipment. You can also personalize your view by nicknaming shipments, adding notes or creating a watch list for monitoring important shipments. Shipments that you’ve sent using FedEx Ship Manager®, added to My FedEx® or tracked with FedEx Desktop may also be viewed and managed via your iPhone. We’ll even let you know if select delivery exceptions have occurred.

Roambi – Visualizer – Roambi is an innovative app that quickly transforms your business reports and data – from many popular business applications – into secure, interactive mobile dashboards, instantly delivered to any iPhone or iPad. It lets you easily view and interact with up-to-the-minute company information – giving you the insight you need for on-the-go analysis, impromptu presentations and smart decision-making. Roambi puts the pulse of your business, in the palm of your hand.

Yammer – Yammer for iPhone is a tool for making companies and organizations more productive through the exchange of short frequent answers to one simple question: “What are you working on?” As employees answer that simple question, a collaborative communication feed is created in one central location enabling employees to voice their ideas, suggestions, feedback, and answers. Anyone in a company can start their Yammer network. However, networks are private and access to each network is restricted to others except to those with a valid company email address with the same domain.

Productivity

EasyTask Manager – Our personal task manager. Very simple and easy to use User Interface. EasyTask Manager supports the GTD (Getting Things Done) method. You can also run it on Mac or Windows. And the best part is that you can sync multiple computers with EasyTask on your iPhone.

Action Method – Action Method Mobile is a free and powerful task management application, designed for maximum productivity. The app also syncs seamlessly with the award-winning online web application, Action Method Online.

Evernote – Evernote turns the iPhone, iPod Touch and iPad into an extension of your brain, helping you remember anything and everything that happens in your life. From notes to ideas to snapshots to recordings, put it all into Evernote and watch as it instantly synchronizes from your iPhone to your Mac or Windows desktop.

Awesome Note Lite (+Todo) – Awesome Note is an innovative note taking application and to-do manager that allow you to combine notes with to-do flexibility. Awesome Note enables you to customize its look with themes the way you want it to be displayed with different folder icons, colors, fonts and paper backgrounds.

Instapaper Free – Save web pages for later offline reading: go to Instapaper.com (it’s free), install the Read Later bookmark, and mark any pages you’d like to read later. Great for long articles and blog posts that you find during the day and would like to read, but don’t have the time when you find them. Save them with Instapaper, then read them when you’re commuting, in a meeting, or waiting in line.

Simplenote – Simplenote is the fast, clean, synchronized notes app for iPhone, iPod touch and iPad. When you download Simplenote, you also get access to our free web app and a growing variety of desktop apps. Your notes will sync securely, wirelessly, and automatically in both directions.

To Do – To Do is a simple, free To-Do list manager written as a favor for some friends. It provides barebones task management. You can add, order and manage your to do items. Basic priority and note support adds extra functionality.

Use Your Handwriting – Instead of typing items in, Use Your Handwriting lets you write them by hand (well, by finger). And no, you won’t be limited to one or two word entries. This ingenious list manager lets you scribble whole sentences, using an exciting method that allows the iPhone screen to accommodate any length of text — when you fill the screen with a word it slides to the left, leaving you more room to write. If you’re a visual person, you can even add a doodle.

Chronolite – Timer – Chronolite lets you run and view multiple timers simultaneously. You can create up to 4 separate timers that can be started, paused, and reset individually or as a group. Timers can count upwards indefinitely or count downwards from a specified time. Each timer can play a customizable alert sound at the end of a countdown.

ShapeWriter – Built on many years of scientific research at the IBM Almaden Research Center, ShapeWriter is a revolutionary text input method that frees you from the constraints and frustrations of a conventional method. Simply slide your finger on the gesture-keyboard and lift to complete an entire word. ShapeWriter’s intelligent algorithms can turn the single gesture stroke into your intended word. For example, a stroke from F to U to N on the keyboard will be recognized as the word “fun”. Ignore repeat letters. For rare names and acronyms, type only once and you will be able to shape write the next time.

Financial

Mint.com Personal Finance – Personal finance tools from Mint.com. Track, budget and manage your money on-the-go. Simply sign up for an account on Mint.com, add your online banking accounts, and access your personal finances anywhere.

PayPal – PayPal’s mobile money application is the faster way to send money with your iPhone® to friends and family anytime, anywhere. It’s much easier than going to the ATM to withdraw cash, writing checks, and sending gifts the traditional way. And you can manage your PayPal account right from your mobile device. All of this with the security and protection you get from PayPal.

Square – Quickly and securely accept card and cash payments for your business, service, charity – even to sell your couch. A free Square card reader makes payments even faster. Generate email and SMS receipts. With Square for iPad, add sales tax and a beautiful list of items sold. Sign on to squareup.com to manage your sales and receipts with an intuitive web-based interface.

Bloomberg – Bring the power of the most trusted source for financial information to your iPhone, along with tools to help you analyze the world’s markets. More than 280,000 professionals around the world trust Bloomberg to give accurate, timely information about the world’s financial markets.

Yahoo! Finance – The Yahoo! Finance App for the iPhone and iPod Touch brings you total coverage from your favorite financial source. You’ve come to expect the highest quality financial coverage from Yahoo! Finance. Now you can get it all in an app built for you. Ranging from broad market indices to the details on a specific commodity, it’s all here. This app has something for everyone, no matter what your need of financial detail may be.

E*TRADE Mobile Pro – Trade anytime, anywhere with E*TRADE Mobile Pro for iPhone and iPod touch. E*TRADE Mobile Pro is one of the most powerful mobile trading applications ever. You get the same core functionality as your desktop, all fully synchronized with your online account in real time.

Zillow Real Estate Search – #1 Real Estate App on iTunes and “Best Real Estate App” by O’Reilly Media. For all U.S. homes (93+ million): Find Zestimate® home values, homes for sale, homes for rent, and more as you walk or drive through neighborhoods using the Zillow iPhone App, featuring built-in GPS technology.

Simple Tip Calculator – Tip calculators are all over the App Store, but none are as simple and easy to use. Who needs a calculator with overly cute graphics, multiple screens or clunky operation? Simple Tip Calculator is just what the name says…a simple calculator. You don’t need a lot of bells and whistles just to calculate a tip and split a check.

CNNMoney – CNNMoney’s iPhone application delivers breaking business news and comprehensive market coverage from the leader in business and financial news. The application includes news, analysis, financial data and original video content—all packaged with the ability to customize your experience and track only the content relevant to you.

myFICO – Estimate your own FICO® credit score for FREE! FICO is the most widely-used credit score in the world. By answering a few simple questions, you can estimate your personal FICO Score. Your FICO score is pivotal – it determines the interest rates you are charged by banks, mortgage companies and lenders of all kinds.

Utilities

iHandy Level Free – iHandy Level (one of the 5 tools in iHandy Carpenter toolkit) is now for free! Take this chance to download! This might be the most beautiful and accurate level you can get in hand. Unlike some other levels in app store, this one is fully functional with calibration capability. It’s accurate after calibrated.

Flashlight – Flashlight fills your screen with bright white light to illuminate your world when you find yourself in a dark spot or concert. Includes fully customizable special effects including: Strobe Light, Trippy, S.O.S., Yin-Yang, ((NEW)) Holiday Lights and more!

5-0 Radio Police Scanner Lite – Tap into the largest collection of live police, firefighters, aircraft, railroad, marine, emergency, and ham radios. Be the first to know about important news, events, or any major crime waves happening in your town.

Alarm Clock Free – Alarm Clock Free turns your iPhone or iPod touch into a beautiful digital clock and alarm clock for free!

Free Wi-Fi Finder – Instantly find FREE Wi-Fi Internet hotspots wherever you are in the world! JiWire’s Global FREE Wi-Fi app uses your iPhone’s GPS and network triangulation capabilities to locate free Wi-Fi Internet access.

Convert Units for Free – You guys asked for it…we’ve added it in this huge update! Custom conversions are here! Create your own unit conversions and convert anything you want! Try it out now! Still and always will be 100% free. Add this useful unit converter to your collection of essential everyday tools. We worked very hard in bringing you an application that has everything you need for unit conversions, while keeping it as simple and user friendly as possible. This is as intuitive as it gets.

Ruler – Now you can use your iPod touch or iPhone as a ruler. How to do that? It’s quite simple! You can measure any object by placing it on the device screen or just next to it. By moving each line limiter one after another you can get a more accurate measurement. In addition it is possible to switch between centimeters and inches on the information screen. Ruler always saves your latest measurement and you can turn back to it any time.

Dictionary.com – Dictionary & Thesaurus – The free Dictionary.com app delivers trusted reference content from Dictionary.com and Thesaurus.com, including nearly 1,000,000 words and definitions and 90,000 synonyms and antonyms. No Internet connection is needed. The app also features audio pronunciations, similarly spelled words and Dictionary.com’s popular Word of the Day that is enjoyed by millions of people.

Free Translator – This application provides an interface to the free Google Translate API for many languages including Chinese, Czech, Danish, Dutch, English, French, German, Hindi, Italian, Japanese, Korean, Polish, Portuguese, Romanian, Russian, Serbian, Spanish and Vietnamese.

Touch Mouse – Touch Mouse by Logitech turns your iPhone or iPod touch into a wireless trackpad and keyboard for your computer. Do you connect your computer to your TV? Touch Mouse is the perfect solution for when you want to stay in control from the comfort of your couch. Point, click, scroll and type in any application—on a Mac or a PC.

Mobile & Remote File Access

Dropbox – Dropbox is the easiest way to sync and share your files online and across computers. App features: Access your Dropbox on the go, View documents, spreadsheets, presentations, videos, and photos; Export files to other iPad apps, “Favorite” files to download them for fast, offline viewing, Use your iPhone camera to take photos and videos and save them directly to your Dropbox, Share and send files via email, text message, or copy and paste links to use in another app, and Swipe your way through photo galleries.

Box.net – Box.net is a web-based service that lets you easily share, manage and access all your content from anywhere. Whether you want to store documents, media or other files, Box.net lets you view, share and collaborate on all your files on-the-go. Best of all, you can sign up for a free Box account.

SugarSync – All of your data at your fingertips…anytime, anywhere, from your iPad, iPhone, or iPod Touch. With SugarSync, instantly access cloud-synced files, photos and music from all your computers. View files and photos, stream music, and share files (and even complete folders) with friends and colleagues – no tethering required.

WiFi HD FREE – Turn your iPhone into a wireless, mobile external hard drive! Works over any WiFi connection. You can now share, copy, and backup your files to and from your PC / Mac / Linux / or another phone! Very easy to use.

FileApp (Documents & Files reader) – Easily copy files on your device for a quick look on the road. Powerful and yet still very user friendly, FileApp will let you find the document you’re looking for within seconds. Copying files over to your iPhone or iPod Touch takes place wirelessly (by FTP).

Jungle Disk – Jungle Disk puts you in control of your data – providing a simple way to backup and access your data from anywhere – even your iPhone!

Transport-App – FREE during the introductory period! Transport is the easiest way to send files to your iPad or iPhone, using the Transport Desktop companion application on your Mac. No hassling with connecting your iPhone/iPad to your desktop, or even connecting to your local network. Just press the hotkey on the desktop or print to the virtual printer and your document is accessible from your iPad or iPhone immediately.

MobileMe iDisk – Log in with your MobileMe username and password (MobileMe subscription required) and you’ll see a list of the folders and files on your iDisk. Select a file to view it on your iPhone. To share a file with someone else, just tap the share icon, choose your recipients, and MobileMe iDisk will send them an email with a link to download your file directly from MobileMe. You can assign a password to keep your files secure and even limit the number of days the download will be available – all right from your iPhone.

ezShare Files – ezShare’s powerful WiFi drive is now free for everyone! Plus test-drive ezShare’s best-in-class file access and remote desktop features.

FilesAnywhere – With this FilesAnywhere app you can view, share and manage your remote files directly from your iPhone. Share files and folders with anyone without any download, upload photos and contacts, and manage your files, wherever you go!

News & Weather

FOX News – With the FOX News iPhone app – receive FOX News Alerts, read fair and balanced headline news stories, stream live video, listen to FOX News Radio, browse through photo galleries, and watch the latest FNC clips on demand, all for FREE!

USA TODAY – The latest news stories, sports scores, weather and photos you’ve come to expect from USA TODAY are now available for your iPhone and iPod Touch. Staying informed on the go has never been this quick, easy or enjoyable.

AP Mobile – AP Mobile offers the world’s news at your fingertips. Personalize your news to meet your needs. You can select local news from your trusted local newspapers and broadcasters and combine it with the best of the AP’s videos, photos, and national and international coverage. AP Mobile — the most comprehensive free news application available for the iPhone — now offers rich media ads.

MSNBC – Download the free app now and immerse yourself in a fuller spectrum of news. Access the day’s top headlines or explore a wide range of videos and stories covering everything from world news, business and sports to entertainment, technology and weather. And with Twitter integrated into the app, you can easily share articles and track any Twitter feed from msnbc.com.

The Onion (News Parody) – This is the official iPhone/iPod Touch application of The Onion, America’s Finest News Source. It is the last bastion of unbiased, reliable, and definitive news in a world dominated by superficiality, mediocrity, and non-Onion news outlets.

The Weather Channel – The Weather Channel 2.81 takes your weather experience to the next level full screen maps, pollen forecasts and more.

Your Weather Network – Watch national, regional, and international video forecasts directly on your iPad or iPhone. You’ll also find customized forecasts covering special events and activities. Your Weather Network brings you high quality forecasts that are a pleasure to watch wherever you go.

AccuWeather.com – Get the “Best Weather on the Web” wherever you go with the AccuWeather.com GPS application for iPhone. This worldwide forecasting tool has all the free features you need to “weatherproof” your day.

WeatherBug – WeatherBug is the only source for truly live, local weather – providing users access to the largest network of professional weather stations in the US and thousands of locations around the world.

WeatherEye – WeatherEye provides FREE detailed current, hourly, short and long term weather information with severe weather alerts and Satellite / Radar maps.

Travel

Google Earth – Hold the world in the palm of your hand. With Google Earth for iPhone and iPod touch, you can fly to far corners of the planet with just the swipe of a finger. Explore the same global satellite and aerial imagery available in the desktop version of Google Earth, including high-resolution imagery for over half of the world’s population and a third of the world’s land mass.

Yelp – Looking for a burrito joint open now? An Irish pub nearby? A gas station you can drive to before your tank hits empty? Yelp for your iPhone is here to help. Use us to search for places to eat, shop, drink, relax and play then read reviews from an active community of locals in the know.

KAYAK Flight, Hotel Search – KAYAK for the iPhone connects to kayak.com, the best travel search engine in the world. Compare hundreds of travel sites at once. Find airfares and hotel prices quickly, for free! Why pay for looking up airfares when Kayak gives it to you for nothing?

Southwest Airlines – Traveling with Southwest Airlines is now even more convenient with our first iPhone app. Make reservations, check in for flights, and access your Rapid Rewards account directly from your iPhone. Plus, our iPhone app has DING! functionality built in, giving you instant access to exclusive, limited-time-only air fare deals. When a DING! fare is made available, you’ll be notified immediately on your iPhone.

Cheap Gas! – Find the cheapest gasoline nearest to where you are! Then, map a route to where the cheap gas is.

TripTracker – Live Flight Status Tracker – Get real-time status for flights, real-time itinerary push alerts, live weather reports, route maps, hotel information and car rental information to make your travel a breeze.

TripIt – Travel Organizer – TripIt Travel Organizer puts all your travel plans right on your iPhone no matter where your travel was booked! Forward travel confirmation emails to plans@tripit.com to build a trip itinerary. Then, access your travel info from your iPhone any time with our free app.

USA TODAY AutoPilot – USA TODAY AutoPilot is your all-in-one trip companion. By gathering your trip itinerary, along with flight status and the current time, AutoPilot organizes your flight, lodging, and rental car details into an easy-to-digest format and consolidates information so that the most timely and relevant information about your trip is always front and center. USA TODAY AutoPilot also offers a suite of travel tools, USA TODAY travel articles and blogs, and photography from Flickr.

SitOrSquat: Bathroom Finder – Quickly find a nearby restroom…and a whole lot more. SitOrSquat is the world’s first wiki for recording and accessing bathroom information globally. All of our toilet finder content is added by YOU, our loyal users. We currently have 65,097 toilets worldwide and we need your help in growing that. Join the SitOrSquat movement!

AAA TripTik Mobile – AAA TripTik Mobile provides latest gas prices, maps, directions, and AAA Approved and Diamond Rated hotel details and bookings. Route to an address, or find and get directions to nearby restaurants, events or attractions. A shake of your iPhone redraws the route from your current location if you get diverted, and also provides voice guidance for your next maneuver. The app identifies your location if you need Roadside Assistance from AAA.

Food

Urbanspoon – Can’t decide where to eat? Urbanspoon can help. Shake your iPhone and the Urbanspoon slot machine will pick a good restaurant for you to try. Keep shaking until you find a restaurant you’re happy with.

Happy Hours – Happy Hours, the nation’s premier happy hour guide, shows all of the food and drink specials going on near you. Click through to see a photo of the bar or restaurant, and details such as the menu, location, amenities, and what other people have to say. Our happy hour ranks are based on the community, so don’t forget to vote up your favorite spots. Happy Hours is powered by GoTime.com and many of the nation’s top print and web publications including the Village Voice, LA Weekly and Phoenix New Times.

OpenTable – Restaurant Reservations – Free, Instant, Confirmed. With OpenTable for iPhone you can make free restaurant reservations at over 13,000 OpenTable-enabled restaurants in the United States, Canada, and United Kingdom. Plus, OpenTable members earn valuable Dining Rewards Points redeemable for Dining Cheques good at any OpenTable restaurant.

Foodspotting – We created Foodspotting to make finding good food easier: Instead of reading and writing long reviews, you can simply see what’s good around you and share photos of foods you recommend. No foods near you? We just launched in January 2010 and are counting on you to represent your neighborhood by sharing your favorite foods and where to find them.

Epicurious Recipes & Shopping List – This app from award-winning food site Epicurious.com includes over 28,000 delicious, professionally tested recipes from renowned magazines such as Bon Appétit and Gourmet, popular cookbooks, top chefs, and leading restaurants. The app works on both the iPhone and iPad, giving you an experience optimized for whichever device you’re currently using.

Healthy Recipes – By SparkRecipes – Looking to lose weight and save money? Cooking at home is one of the easiest ways SparkPeople members do both! Our Healthy Recipes application lets you browse and search more than 190,000 recipes, plus save your favorites. You can browse by course, ethnicity, preparation time, and more. We also provide calories, carbs, and 10 other key nutrients for each recipe.

Food Network Nighttime – Hooked on the Food Network? Can’t get enough of your favorite Food Network stars? Then this is the app for you! Food Network Nighttime delivers the best of Bobby, Duff, Giada and all the rest of the Food Network gang right to your iPhone.

Sushipedia – Sushipedia opens a whole new dimension to the fascinating world of sushi dining. Whether you are the type who enjoys the occasional sushi experience or an avid sushi aficionado, Sushipedia can greatly enhance your enjoyment and knowledge of sushi culture. Drawing up a wealth of resources directly from Japan and the USA, Sushipedia now boasts the most comprehensive and accurate worldwide reference for sushi facts and information.

170,000 Recipes and Grocery – BigOven – Ever want access to your cookbooks from the grocery store? Try BigOven 170,000+ recipe search. Find virtually any recipe, and build a grocery list that you can access on your iPhone and the web!

Hello Vino – Wine Recommendations – Hello Vino is a FREE wine app for your iPhone or iPod Touch. Whether you’re looking for a wine to pair with food, enjoy wine on its own (by taste or flavor), or give wine as a gift, Hello Vino will provide you with wine recommendations.

Audio & Video

Pandora Radio – Pandora Radio is your own free personalized radio now available to stream music on your iPhone or iPad. Just start with the name of one of your favorite artists, songs or classical composers and Pandora will create a “station” that plays their music and more music like it.

SoundHound – What’s that song? Who’s that hot artist? SoundHound knows. And now, everyone can enjoy 5 free IDs each month – and unlimited lyrics and browsing – from the famous SoundHound ∞ instant music search and discovery app.

Shazam – Lovin’ that tune? Shazam gives you instant satisfaction when you want to know what song is playing. Just point your phone towards the music source to identify and buy the track, or share your discovery with friends and family.

Last.fm – Listen to more than 5 million tracks for free with Last.fm on your iPhone. Create personal radio stations based on any artist or genres, and listen to commercial free music for hours. With Last.fm on the iPhone you can also check out artist bios and concert information and share your favorite tracks with your friends using the iPhone contact list.

Slacker Radio – Listen to free personalized radio on your iPhone, iPod touch and iPad. The award-winning Slacker Radio App gives you access to the entire Slacker music library featuring millions of songs from thousands of artists. Listen to over 120 expert programmed radio stations or create your own custom stations. Slacker Personal Radio is the best way to discover new artists and hear your favorite songs. Best of all, with a Slacker Radio Plus subscription, you can store your favorite Slacker stations on your iPhone, iPod touch or iPad and listen even when you don’t have a wireless or Wi-Fi connection!

iheart radio – iheartradio delivers over 750 of America’s favorite radio stations right to your iPhone or iPod Touch. Bookmark your favorite stations, tag songs for purchase on iTunes and view lyrics to your favorite songs. iheartradio also features the best selection of exclusive digital stations including Slow Jams, White House Brief, erockster, Pride Radio, Smooth Jazz, AT40 with Ryan Seacrest and some of the top talk stations in the country featuring Rush Limbaugh, Glenn Beck, Dr. Laura and many others. All stations are streamed in Apple’s high-quality AAC format for a superior listening experience.

Air Video Free – Enjoy your entire video collection everywhere! Get more of your video library on your iPhone, iPod touch or iPad. Air Video is a great solution to watch your AVI, DivX, MKV and other videos.

iTalk Recorder – WAY more than a “voice recorder”… whether you just want to recall a conversation later, or are serious about capturing the sounds around you, Griffin iTalk is the app you need for your iPhone or 2G iPod touch (2G iPod touch requires Apple Stereo Headset or similar compatible headset).

Knocking Live Video – Knocking is like having a live mobile phone web cam. See instructions below. See what I see, LIVE anywhere 3G or Wifi iPhone to iPhone. LIVE VIDEO! Works on all 3G and 3GS iPhones and iPod Touches can even receive.

Record Video On iPhone 2G/3G – iCamcorder Lite – Record smooth videos with high quality audio on your iPhone EDGE, 2G or 3G device! The impressively smooth recording at 15fps adds a valuable feature to your iPhone, that you don’t want to miss in the future.

Conclusion

The 100 free apps above should be enough to keep you tapping away for quite some time. Let us know if you’ve tried any of these and what you thought of them.

Also be sure to mention any great free apps that we missed!