Check out this browser based Chess implementation. The site is in French, but it's pretty easy to work your way around.
The first player to the site gets a URL to send to the second player. Once the second player visits the URL, the game is on. Moves made by one player are seen on the other players web-browser immediately. Very smooth. Written in jQuery.

Comments
Hello,
This game has been rewriten and is now open-source.
A new english demo is available: http://chess.diem-project.org
Download and documentation: http://diem-project.org/plugins/dmchessplugin
Cheers
Thibault
Excellent, thanks for the information Thibault.
The links is broken.
Thanks for the heads up. Looks like the actual site is still up, but the demo is down.