This one has a couple different cool things. First, if you follow the pink dot moving, the dots will remain pink, but if you stare at the plus sign in the center, the rotating dot will turn green. That's cool, but now try this... focus on the plus sign in the center for a short period and all the pink dots will disappear and all you will see is the green dot going around! cool huh?

Pink Dots Optical Illusion