Ours come up with more and more disturbing plans to take over the world. We try to keep them busy.
Another good thing is documentation. We lost most of our programmers this year, but thanks to documentation (and the fact that they are teaching weekly classes to newbies until they leave for College) we are going to be ok.
FInd some reusable bits of code for them to improve upon. A favorite of our team is the joystick conditioning code.