At a certain point the list of forums grows too long. We use phpBB at work and experienced just that. Then we went herarchical (enabling sub-forums) which made it much easier to get an overview of the forum. I recommend considering this at some point.
About the mod:
http://www.phpbb.com/phpBB/viewtopic.php?t=265040
Example:
http://ptifo.clanmckeen.com/
