Also, the "change username" command doesn't work. It's not needed, but just something as simple as being able to add "AFK" would be nice.
Mod edit: we understand that, but in the past when it was possible for people to change usernames in chat, there were incidents of people pretending to be other users, which led to problems, since new visitors to chat (arriving after the name change happened) had no idea that they were talking to someone just pretending to be Adariman, and not Adariman himself.
If you're going AFK you can either just say so in chat (which is a good idea in any case) and with any luck your "going AFK 10 minutes" post will be visible to others if they bother to scroll back, or you can just log out and log back in when you return.