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.

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.