>Excellent. It was already there, I just wasn't seeing it. I should review the list of available forums once in a while.

You only have to do it once. Then, from then on, if a new forum gets added, you are opted in by default. Then, if not applicable, you can turn it off. Pretty much in the same way as a category you would like to filter out. You inherit from a new category at first but can later decide to filter it out.