Chat rooms can now be tagged! You can add tags to a chat room while editing the description. This is more for the scoped chat rooms for sites like Stack Overflow that have such. It allows linking between the tag on the site and the corresponding chat room to be much easier.
One problem, though, is that tags are... slightly permanent. Once a room has tags, it cannot have tags removed unless at least one tag remains. So if it only has one tag, that tag cannot be removed, it can only be replaced. If it has more than one tag, you may remove as many tags as needed as long as you leave at least one remaining.
This has caused a lot of general, not-really-tag-worthy rooms to be stuck with tags, however pointless they may be. It would be better that we be able to remove all tags from a room if there is no reason to truly associate tags with the room.