Fun Optical Illusions to Amaze the eyes
Created by a Japanese professor of Psychology Akiyoshi Kitaoka.
Click to Open from His home page or the artcyclopedia
There are a million, visit his page and click all night...
Here's some from the Exploratorium
Bird In a Cage
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