Cool Optical Illusions....
 

http://www.switched.com/2009/08/20/12-more...s-on-the-net%2F


This one is pretty cool....


https://www.blogcdn.com/www.switched...illusion11.jpg

I like the falling ball one. Playing with the right slider makes it move back and forth.

The spinning disk one you posted doesn't seem to work on me at all unless I look back and forth straight left to right. Looking in a circular motion doesn't do anything.