Well here is an idea. If you really wanted to screw someone, you could load u3 thumbdrives with a hacksaw and switchblade and sell them to people on ebay.......i bet you can see what I trying to get at....if you don't the person who buys the drive and puts it into their computer would become infected....and every other computer they put it in!
note: I would do this myself...just wanting to see if anyone sees the dangerous potential of this.