Embedded Projects Research

I'm considering offering a course consisting of a series of embedded systems projects chosen by students to fit a certain theme. I think it would be useful to test out the concept with some students this semester (Fall 2013) to give me a chance to debug the methodology before the class is offered in the Spring.

The idea is to have 4 weeks to work on a project, with regular presentations, design reviews, and critiques. The only requirements for the project are that they use some digital controller and they must accomplish something cool and intersting receiving input and providing output to the user/viewer. If you have an idea for a project that fits this description, then I'd love to hear about it.