There are a couple of small forums I visit that target particular interests of mine. They are well run forums with supportive memberships. But they're privately owned. And there's a constant drumbeat for donations. Sometimes they achieve their monthly donation goals. But often it seems they don't. So I always wonder just how long they'll be able to keep going, although it does appear they seem to keep moving along... at least so far.
I used to be very active here when the forums were still a part of Psych Central. But, since the changeover, I seem to find less-&-less that is of interest or that I feel I have anything useful to contribute to. Occasionally I'll rip through the Games forum. But I can only do that once in a while. Otherwise it becomes simply a bore.
One thing I have noticed, with these other forums I mentioned, is that on each one there seems to be a core membership who've been on the forum for a long time & have gotten to know each other well. It can be very tough to break into that circle & become anything beyond "just another newbie".