Cheap Robot Kits?

Defusion_Dunk asks: "Having just watched a re-run of "Short Circuit", and in particular the scene where Steve Guttenburg is teaching the robot arm to play a keyboard, I would like to know: Does anyone know where I can purchase a cheap robot arm that I can plug into my PC and do neat things with? For some reason I have always had a dream of having my computer open a can of Coke for me.... " I remember building a small robot as a science project waaay back in junior high school, and the experience of building it was educational and fun. Does anyone have any pointers to such kits that may still be available today?