There was an entire page of this on yahoo today, this one peaked my interest. I just didn’t get how people thought it was going in the other direction.
Image created by Pech Misfortune, via Mighty Optical Illusions
A variation on a classic illusion, this cat can be perceived as rotating in either direction. With practice, you can make it switch at will!
For more optical illusions click the link: Brain Teasers and Optical Illusions