Blind Spot - Seeing more than your eye does - Interactive

Most people (even many who work on the brain) assume that what you see is pretty much what your eye sees and reports to your brain. In fact, your brain adds very substantially to the report it gets from your eye, so that a lot of what you see is actually "made up" by the brain.

http://serendip.brynmawr.edu/bb/blindspot1.html

Also see : http://serendip.brynmawr.edu/bb/blindspot/

for an Applet that allows you to map you blind spot.