ILLUSIONS, Michael.

CollegeHumor.com has a great gallery of mind-melting illusions. If you dig stuff like this, you've probably seen most of them before, but they're no less effective the second time around.

This one in particular is fantastic:

• Read 13 Optical Illusion GIFs That Will F**k With Your Brain at CollegeHumour.com

Also good:

Nothing Travels Faster than the Speed of Light, Mr. Presidennnnt Fuzzy Wuzzy Was a Woman? Dodecabrainmelt This Calligraphy Leaps off the Page