I printed out one of those dragons a while back. It's pretty cool, but maybe not cool enough to show other people.
pastorofmuppets - 2010-01-18 I should clarify. I was joking about the dragon. This video is hella cool.
dbtng - 2010-01-17 I had to drag the video back and forth several times to get my eyes to work right again. I've seen 3d sculptures of Escher's impossible shapes. Same effect as this. You just can't force your eyes to interpret it properly.