I found this great site that has an online chess-playing AI. What's cool about it is it shows you the moves considered. I plan to show it to my AI classes to demonstrate search at a very high level.
You can play at http://www.turbulence.org/spotlight/thinking/chess.html
and watch the AI think as you play!
At the gallery, you can see snapshots of the thinking:
Above is an image from early in the game, below an image from near the endgame.