That's a fun trick that our friends did up there on the metro-rail. One time, we got on a metro-rail train, and poured out a box of paper clips onto the floor. When the train started up, I sat there with the cam-corder taping the the dance that the paperclips were doing. I'll hafta dig that tape up and digitize it. It's quite funny, especially the reactions of the other riders when they were moving on their own. When the driver would apply power, they would bunch up, and then when he started braking, they would fly apart, almost like they were in some type of clay-mation animation skit!