I saw that and thats what kinda.. Inspired, if you will, to make this thread.
EDIT: Heres another one, kinda hurts your eyes:
http://www.graphicsdb.com/data/media/580/3D%20Waves%20Optical%20Illusion.jpg
EDIT EDIT: Yet another one:
http://www.optillusions.com/dp/1-41.htm
None.