In the second "Back to the Future", the flying skateboard was indeed very cool. I looking at Popnext and actually saw a company that sells plans to build something that's remotely similar. Unlike the one in the movie, theirs is based on an air cushion, like hovercrafts. I don't know if it really works, but I did some skateboard myself and this seems to be a great way to either waste your money or go to the emergency room (I guess that money would be wasted there as well).