Is there a way to show how many users are currently online on the RM, similar to the forum statistik on the forum home page? But it needs to display only those users, who are reading in the RM, not those in the forum.
You can make a suggestion about it, though I don't recall any other mentions of this sort of thing. Note that the members online widget is not limited to people online in the forums section -- it's anyone using any portion of your XF install (so help pages, registering, search, member profiles, etc). I can't really see the context/meaning of that widget changing, even if we did add more specific tracking.
The closest existing suggestion that I can think of relates to people wanting online counts for individual forums.