I recently found that this site (meta) has a chat room permanently attached to it:
Welcome to chat for: Mathematics Meta
This is a general discussion room
Nobody posted there for 829 days, but the room did not freeze for inactivity: apparently, the "official" chat rooms never freeze the ...
Behaviour asked: Can this room be a useful addition to the main chat room?
The question is: 1) What will be discussed here? 2) Will people come to this chatroom?
I am not sure, but I suppose that when a user comes to chat, by default they are shown the list of rooms associated to math.SE and this room is associated to meta.
I am not sure whether this room is shown in the side bar of the questions or whether only the room associated to the main are shown there. (There does not seem to be much about showing chat rooms in the sidebar on meta.SE.)