Powers of 10 (http://www.powersof10.com/)
Powers of 10 video (http://www.youtube.com/watch?v=L7Y_ylA_PiY)
Powers of 10 (http://video.google.com/videoplay?docid=-4150268891643565896&q=powers+of+10&total=5775&start=0&num=10&so=0&type=search&plindex=1) - speedier video
The Simpsons' version (http://video.google.com/videoplay?docid=-4024033032576529955&q=powers+of+10&total=5775&start=0&num=10&so=0&type=search&plindex=0)