Here are a few things that I think would make it better:
1) when you rollover the top menu-bar in the HTML page (outside the Java Applet) the applet vanishes, then comes back when you are no longer over the menu. I think this is probably a hidden-div thing. It's pretty annoying, but avoidable.
2) A "play again" button would be nice, so I don't have to use the above menu
3) Constraining the engine to specific openings would be a great feature -- even if the feature is very limited (eg. can only choose White's first move).
btw: what chess engines are behind the various playing levels? Or what are the settings for those levels? The "beginner" engine doesn't play a horrific game, which is rather nice for toe-dipping back into chess.
Thanks again for the wonderful site.
--stadjak
(btw: also very nice that the Forum is integrated into your account so I didn't have to sign up twice)