Ask HN: Android project for introducing teenagers to programming?

I'm one of the founders of ImagineK12-backed Tutorcloud.com. We've been talking to lots of parents who want their kids to learn a little programming. We'd like to help them, and we need your help.

Specifically....Recommend a project we can use in our Intro to Android Programming workshop.

These kids are 12-16 years old. No programming experience. Eager to learn. Dying to build "cool apps". What could we build with them?

The workshop is only 4 hours long. Can we build something kids will think is cool in that time?

Comment here, or contact me directly. And if you're interested in teaching teenagers in the Bay Area, or online, drop me a line as well. [chris@tutorcloud.com].