The RAGE team holds an annual teambuilding weekend in the pre-season to help students and mentors get to know one another better. One year they spent the weekend at a camp working together doing teambuilding exercises. Last year they partnered with local organizations and built a handicap ramp for a wheelchair-bound resident in our community. Throughout the pre-season, every meeting is started with a short teambuilding exercise. These weekly exercises can be easy to organize and cost little to do.
See the presentation (
http://www.usfirst.org/robotics/2005...%20handout.pdf) that was made on Teambuilding at the 2005 FIRST Conference or PM me for more ideas.