Eyetricks.com
Collection of illusions and other mind teasing oddities. Includes illusions that you can make.

Akiyoshi's Illusion Pages
Includes anomalous motion illusions.

The Exploratorium's Online Exhibits: Seeing Exhibits
Interactive illusions from the exploratorium.

Colorcube
Illusions organized by category, including blind spot, blink effect, bordering, chromatic adaptation, colorblindness, and others.

Magic Eye Image of the Week
Includes a new image every week demonstrating stereograms.

Sandlot Science
Interactive optical illusions, games, science projects, fun puzzles, and distortions.

Illusion Works
A multimedia museum of optical and sensory illusions, with on-line demonstrations and explanations.

M.C. Escher
Optical illusion art, news, history, copyright and foundation information.

Counter-Rotating Spirals Illusion
Java applet, including other illusions, such as an animated Necker cube.

NIEHS Kids Page -- Optical Illusions
Presented by the National Institute of Environmental Health Sciences. A collection of illusions.

Eye Magic
Collection of high quality optical illusions that come with clear explanations.

Eluzions' Optical Illusions
Contains many optical illusions, illustrating a wide range of visual anomalies and surprising optical effects. A free screensaver, posters, and educational explanations are also provided.

Optical Illusions
Some classic optical illusions with explanations for how they work.

Crazy Images
Interactive animations and optical illusions that respond to user's input.

Eyetricks.com: Optical Illusions
Collection of optical illusions, brain teasers and games.

Khushboo's Virtual Escher Gallery
Small selection of images by the artist.

Visual Phenomena and Optical Illusions
Interactive illusions, including Benham's disk and other illusions involving motion.

Optical Illusions
From the Department of Ophthalmology and Visual Science at the University of Illinois, a collection of illusions and after images.