Robotics competitions (Score 1)

Lego Dacta is not cheap, but really gets kids involved. I usually follow it up with Floppy the robot, a simple bot built with a 3.5" floppy drive. Competitions are really addictive, I either invent one for the group like climbing to the top of a ramp or navigating a maze. Destructive competitions tend to leave out the girls..... To get them really hooked, try the Boston University Design competition (http://www.bu.edu/eng/design/rules, or the University of Vermont DesignTASC(http://www.emba.uvm.edu/TASC/2004/index .htm)