There is a new forum started by refugees from photo.net called The Underground Leica Forum. It is called the Leica forum only because many of the participants became frustrated with the moderation on the photo.net Leica forum. Many of the participants are active large and medium format photographers, and there is a category for large format. The intent is not to compete but to compliment other forums.
I will warn you that the moderation is looser than other forums too, and there are some wise-guys. But there are also some excellent photogaphers and wide ranging discussions, which makes for an enthusiastic and intimate online community. Check it out if you're curious.
(Q.T. - if this is out of bounds please delete my post. Thanks, Frank)