Illusions

Optical Illusions  (Y,M,O,T)
Optical Illusions, Visual Oddities and Tricks for your Eyes and Mind

10 Mind-Melting Optical Illusions That Will Make You Question Reality  (Y,M,O,T)
From Science Alert.com

Exploratorium  (Y,M,O,T)
An online science museum of optical illusions

IllusionWorks  (Y,M,O,T)
"the most comprehensive collection of optical and sensory illusions on the world-wide web"

SandlotScience  (Y,M,O,T)
Online science museum with both online and downloadable illusions