Hmmm...
Actually, I have left it at the two main forums. There are more than that, but most of them are for announcements (What this board is about, upcoming workshops, favorite books and links, etc.) and for archives of old discussions.
One thing that has seemed to help have been the interviews I have been doing. They seem to enliven the discussion and give it a focus. For instance, this one on
Balance is the Booby Prize.
The reduced number of "active" forums has helped.