I pick Gabbly. RSS Feeds, Muting... what's not to love.
I was going to say the advantages of IRC, but I just looked at the Gabbly API and it's an easy pick.
Plus, IRC loads slower and asks for security stuff.
But Lack... if you are going to do it...
MAKE SURE YOU Set the follwing variables in the url:
nick = (name)
dnc = true
http://www.gabbly.com/gabbly.pbwiki.com/Dev%20Corner
PLEASE!!!
This should help cut down impersonating, it wont eliminate it but it will help.
EDIT: Oops, your one step ahead of me...
Also, for private chats you can pass a key and append it to the conquerclub url.
Note:
Gabbly is a new, more features will be added in the future.