Question: How does the Active User link at the top of the Forum page work? Sometimes, I see that it says there is only one user, but I see new posts happening.
It's based on when they access the main forum page in the past 7 minutes or so. If they're on a topic and replying and taking a while, that could time out, and they'll still be able to post.
I fixed a bug recently, where it wasn't keeping track of user's last accesses if they joined after April 2005 or so. We should see a lot more current users now.