Well it's an automated PBEM server I've been working on. So it is PBEM, but I reckon it's very nearly as convenient as TCP/IP. You can see the website at
www.llamaserver.net.
Basically it checks its e-mail every 5 minutes, keeps track of who's sent the turn in, and hosts when they're all in. It checks the files as they come in so it knows automatically what game they're for, and it sends confirmation e-mails straight back, or lets people know if there's a problem.