So maybe a feature that would show if a user isn't currently active (as in if they've been viewing a forum thread or the forum home page for a while it shows their status as idle.) Is that what you're suggesting?
Viewing post in Forum Suggestions
Well, I guess two things.
1) An icon by their name indicating if they're online (viewing the forum) or not.
2) A list or count of users currently online. I like the simple look and feel of the forums so far, so I wouldn't really sacrifice that for a long list of names, but knowing how active the forums are would be nice for maximizing views and activity.