Optical illusions
Examples:



EDIT: You should really try this one!
Look at the dot in the middle.

Then move your head back and forward, and it appears that the circles are spinning.
EDIT 2:
Posted 22 May 2009 - 01:00 AM




Posted 22 May 2009 - 01:07 AM
Posted 22 May 2009 - 02:40 AM
Posted 22 May 2009 - 11:09 AM
Posted 22 May 2009 - 12:37 PM

Posted 22 May 2009 - 12:47 PM
Posted 22 May 2009 - 01:42 PM
Posted 22 May 2009 - 01:58 PM


Posted 22 May 2009 - 02:57 PM
Posted 22 May 2009 - 05:47 PM