Thinking Machine 4 is a cool little flash widget which shows you how a computer computes its next chess move.
The site has this to say about its little project,
What do the images mean?
When it is your (White's) turn to move, the chess board will gently pulse to show the influence of the various pieces. in the left image below, you can see waves over the squares around the king and (very lightly) over the squares where the pawns might capture. When the machine (Black) is thinking, a network of curves is overlaid on the board; see image at right. The curves show potential moves--often several turns in the future--considered by the computer. Orange curves are moves by black; green curves are ones by white. The brighter curves are thought by the program to be better for white.