The tavern thread itself, I guess, is the closest thing. Read the last few pages, see who's posting... of course, if someone enters, introduces herself, and then stays fairly quiet you might not notice her, but otherwise, it's not a bad indicator.
Maybe the best answer would be to have a "Red Dragon Inn" post in the Character Tracking and Interface Thread, along with someone to keep it up. Active characters could be "In the main room" even if they technically aren't. Inactive characters could be "taking an extended rest in their rooms".