If you've got a great idea for an Android app but are somewhat lacking in the coding skills requires to create one, Google's Android App Inventor is a great way to get your hands dirty. At least it was, until Google pulled the plug on the service last year, giving registered users time to download their projects before hand. In a fit of charity, they posted the open source code for the web and desktop software to let anyone host and run their own clone of the service - a challenge which the Massachusetts Institute of Technology has heartily embraced.
Prospective inventors can hop over to MIT to try the revived App Inventor. It even uses your familiar Google login to authenticate, though of course any projects previously stored on Google's servers are long gone. It's a great idea for a technology institution to implement for its students, but making it open for everyone is a downright public service - good on ya, Beavers.
If you're unfamiliar with the App Inventor, it allows users to create self-contained APK files with a "what you see is what you get" interface, creating a (relatively) user-friendly way to make basic applications. Completed apps can even be posted to the Android Market. Built-in API calls allow even novices to implement advanced behaviors using available hardware, though the possibilities are nowhere near as complex or optimized as native development.