As of now (11pm Pacific Time), a temporary/test/silly/whatever-it-is chat room called "Room for coredump and Jacob" has taken over from "Vote to Close" on the right sidebar.  

Ok, since "useful" seemed to be problematic:

"The Comms Room" is the most active SF chat room and "Vote to Close" is the only other SF chat room that gets used a lot.  Could something be done so that those two show up on the sidebar instead of whatever joke or temporary chat room de jour automatically pops up?  I don't care if it's really "permanent," I just don't think throw-away chat rooms should show up there at all.