I ran into this website via a SomethingAwful thread, it's a test of whether your left-brained or right brained.
Left-brainers are more logical, tend to see patterns easily; the left brain is also the side which generates words and language. Right-brainers however, are more feeling-oriented, they easily recognize symbols and images, and have good spatial perception skills.
Most people look at this and see the dancer turning counter-clockwise at first (left-brain), if you instantly see it one way...then try and focus to make it change direction. It's fun for the first 10 minutes, but then you start to get a headache lol.