I thought it'd be cool to have a thread where we can discuss popular apps on iOS / Android that are cool / unique. So, here's some I think are pretty noteworthy!
Viggle - If you have an iPhone and you don't have this, you're doing it wrong! Basically this app rewards you with "points" for watching TV and ads, and you can cash in those points for rewards (like BestBuy gift cards!). As you watch, you can do things like play trivia, watch commercials, or share your "check ins" for extra points. It's really cool, and very much worth it (especially now with March Madness winding down, points are everywhere!).
Nike+ - I believe this is available for both iOS and Android. It's an awesome running app that tracks distance, pace, route, time, and a bunch of other things (like calories, etc). Very great app for tracking your progress if you're trying to get into shape. Also has an awesome "tag" feature, where the person who runs the shortest time or distance becomes "it" and must run longer to make someone else "it". Really fun stuff and helps to push you!
Zombies RUN! - Great game! As you run (or walk) you'll pick up supplies that you can use to build up your encampment and bolster your survivor count! Between songs, you'll be treated with little story tidbits that flesh out the universe, telling you about other camps, and giving you missions to run. If you turn on GPS, you'll get "Zombie Chases" where you have to turn on the heat and out run a zombie horde (it'll track your pace with GPS, so RUN!). Very fun fitness game
Draw Something - Fantastically fun game with "charm". Basically you pick a word, and draw it, while the other player guesses what your drawing is. Since its all "finger drawing" nothing is outrageously good and artistic ability isn't super necessary! Very fun game, and you can play between platforms! Check it out (it's free!).