The cross-platform Corona SDK has all the usual features for creating an app that runs on iOS, Android, Kindle Fire, and Nook, along with one indispensable addition: a physics engine. Corona apps can take objects and simulate them bouncing around a real world. Writing your own Angry Birds-like game is much easier.
The company also offers a cloud for storing information from your game. Access is simple from the app code. You'll find the usual repositories for bits as well as custom formats for game builders. Your code can create leaderboards, track achievements, offer chat sessions, and integrate with social networks, all through the Corona cloud.