I read about this optical illusion on Digg, and the video demonstration of it is pretty crazy. Essentially, sculptor Bryan Parkes and manufacturer David Burder have taken a hollow mask shaped like Einstein, turned it around so that you're looking at the inside, and then put it up to the light... and the effect is SPECTACULAR! As the video shows, when you walk around the room, the head looks like it's turned towards you-- not just the eyes, but the whole face. Pretty crazy. Link via Digg.