Project Paw Print
Eventually, you run out of things you can do with a single robot!
A global vision system is something we've always wanted to make. Finally, we got past our fear of vision processing and troublesome webcam drivers enough to create a system which instructs an arbitrary number of m3pis to form a stationary, balanced formation.
The exciting part of our application is how any number of robots (well, up to 64) can be used at any time. The pattern on top of the robots (called a paw print) identifies each robot's radio channel, so that each robot can be instructed to proceed to its proper destination in the arena viewable by the overhead camera. The main vision server (i.e., our laptop) counts the number of visible paw prints, identifies them, and assigns them a position in the arena. This means that you can physically remove or place any number of robots in the arena at any time, and the robots will automatically balance their formation on the fly.
Source code for Paw Print is available here.