Last weekend, we had a joint build session with team 3613, TBA (Tee-ba), who graciously agreed to drive 2 hours (each way) with the promise of free food. The outcome was 2 major projects:
1) A candy counter, which sorts black & white chips onto opposite sides (black and nothing tilt the sorter on the same side). The original intention was to count the objects in each cup with a limit sensor, but we ran out of time. We also would have liked to add a second sensor so that two whites in a row don't require the sorter to reset each time. The line tracker sensor worked better than the light sensor. You can see the action at:
http://www.youtube.com/watch?v=VwY7UBjGvRk
2) A dual differential drive, which was not completely functioning by day's end.
Unfortunately, the projects required the kits of both teams with borrowing of parts back and forth, so they had to be disassembled at the end of the day
However, I thought it was a rather productive effort for one afternoon.