The notification "You have got a private message" must be on absolutely every screen, no matter what the person is doing, admin, spellcheck, reading messages, whatever.
I suggest to accompany this with some sound (the user can turn this feature on or off).
Only then the communication can be instant and is just as useful as fancy popup windows or so. So users will start talking to each other, this simple feature will greatly change the interactivity of the board.
Of course the next logical step would be "invite to private chat", but this is additional work and not necessary, hurling private messages back and forth is a good start. Of course, the correct way would be to logically separate messages and online chat. For example, if you exchange 20 messages and you send out 20 email notifications, this would be obnoxious
Right now, I can see who is online, but there is no easy way to contact those people.
I insist so much on these types of changes to be done by YOU, because they permeate the entire program, so user hacks are not feasible.
