Hello!
This summer, I've done a chatserver running a protocol a friend and I have come up with. We call it SCC (I've forgotten what that stands for )
I would be glad if you could post what you like about the protocol, and if someone wants to program a client, then I'll be much happy! I already have a basic client, but it only supports roomchat etc.

The server supports:
Room chat, private chat, accounts, mailboxes, server & room modes (like Server Op, Server Admin, Room Op etc), contactlists, status messages, and much more.
Here's the complete (i think) documentation of the protocol:
ftp://pbsoftware.mine.nu/SCC/sccdoc.txt
Don't care about the text under "TODO", its probably in Swedish :P

Please, tell me if you're interested

ps: the server is programmed in C++, and is fast.