FitFu

[FitFu is now closed. Here's the original description. It was one of the first gamified fitness apps] * Track your motion Using the accelerometer on your iPhone or iPod Touch, FitFu gives you feedback to help you keep going and reach your goals. * Celebrate progress with friends Friends are the key to sticking to your goals, so we've made FitFu social; whether you want to cheer them on, thank them for help or just compare your progress. * Discover a new way to stay motivated The more you and your friends are active, the higher your level and the higher your points. Unlock new content as you progress. * Stay active wherever, whenever No more being tied to a games console or a gym, now you can stay active wherever you are - be that your bedroom, your office, a hotel room or in the cabin of your Mississippi boat.