Fun Optical Illusions to Amaze the eyes

Man these are cool.
Created by a Japanese professor of Psychology Akiyoshi Kitaoka.
Click to Open from His home page or the artcyclopedia
Acorn Storm
Rotating Snakes
The Bulge
Uzumaki ampan
Motion AfterAffects
There are a million, visit his page and click all night...

Here's some from the Exploratorium
Spinning Palm
Bird In a Cage
Depth Spinner

Not as cool as Kitaoka, but worth a look: Visit this site's Home

And finally, The worlds smartest bird. It's a video, wait for it to load, it's worth it