clockwise only. i cant even begin to imagine how it would be the other way.
nice tits.
It took a while but I got her spinning both ways (initially clockwise). Whichever way she spins you can't see how it could possibly work in the other direction. But it does!
Here is another good one. Which square is darker?
[url width=200 height=268]http://i141.photobucket.com/albums/r66/batch_2001/chess.gif[/url]
Are you sure? They are the same. Check it out by sampling the colours in you favourite paint program.
One thing I've never been able to see was the 'magic eye' pictures that were popular in the early 90's. Though not really an illusion as such I suppose.