For general vision information and stereograms, http://www.vision3d.com
Highly recommended for optical illusions: http://www.illusionworks.com
An illusions gallery at http://dragon.uml.edu/psych/illusion.html
Subjective contours at http://www.slc.edu/~ebj/sight_mind/subj_contour/
The Color and Vision Research Laboratories of the University of California, San Diego have this quite brilliant site which is a must see for teachers and students of visual perception. http://www-cvrl.ucsd.edu/
Neuroscience for Kids is a site with an anormous amount of information on the brain. Take a look at http://faculty.washington.edu/chudler/introb.html
Watch this space for more great psychology links