Here's another optical illusion. Stare at white spot in the center until the video ends. The closer you get and the more of your field of vision you fill with it, the cooler the result. (No scary monsters pop up or anything, don't worry.) When it ends, look around.
This is camouflage rather than an optical illusion per se, but a Japanese designer has come up disguises for hiding from criminals in urban areas. Pictures here and article here. (Via News of the Weird Daily)
Remember the spinning dancer from a couple of weeks ago? It's been discussed pretty widely on teh interwebs, with perhaps the most interesting phenomenon being those people who insist that the image is programmed to reverse direction. (They're probably the same guys who insist everything is Photoshopped.) They come across as some lonely and angry dudes, since all you have to do to disprove that is watch it with another person. But Matthew Lewis proves they're wrong here anyway. And here's an intelligent discussion of how our brains pick a direction to see her spinning in, with a debunking of the bogus left-brain/right-brain claims of the original article.