Here's a fun site! or do I mean sight? "50 optical illusions and visual phenomena". Always fun seeing the vagaries of human visual perception - we're so inclined to think that "seeing is believing". A concrete example of the illusory nature of human experience. Perception, and memory.
I particularly enjoy the way the eyes follow your mouse arrow around the screen!

Wired have an article about a small study where brain imaging technology showed clear differences in the brains of people who were lying compared to those who were telling the truth.

ScienCentral have a report on another imaging study, showing the sight and smell of food can trigger an area in the brain to light up in much the same way it does when substance abusers talk about their addictions, suggesting that overeating may be a biologically wired impulse in some. (No surprise to me!)