Thanks for a great website. The diplomacy page especially makes it easier to keep track of a conversation thread. I do have some minor improvement suggestions though.
Not really a suggestion, but I found a typo in the <title> when reading a message, diplomatic is spelled 'diplimatic'.
The timestamps on messages sent and received don't use your personal timezone setting.
In the reply-to screen, it would be nice to have the message displayed above the textarea, just to refer to it if it's a long message.
Lastly, a feature request. It'd be interesting to be able to click a player name, and see a list of the games that they're involved in (yes, I've tried to suss out another player's performance in other games before!) This would come close to ranking players without actually having a ranking system.
Anyway, hope some of this is of use to you. Keep up the good work!