Illusion

Optical Illusions - Contains the best optical illusions, illustrating a wide range of visual anomalies and surprising optical effects. They fool your mind into seeing a false reality. Identical lines will appear to be different lengths, ghostly dark blobs appear where the screen is white, black and white patterns appear to move when they can't, etc. They can be so convincing that you may have to check for yourself that there's no trickery involved! From EncycloZine (Y, M, O, T)

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

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

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