It would be nice to see who has been “afk” for a while in chat channels. Even doing it crudely on the client side would help.
It could only show people to be non afk if they have sent a message to that channel in the last N minutes.
I like how KGS fades the names a little bit when people are AFK.
Another thing would be to show if a user has left the chat after messaging the chat channel.
I have many times typed something to someone and then realized that they are gone.
All the messages from a user that is no longer in the chat channel, could also fade or otherwise change colour(just slightly enough to notice)