This is the only photo site I've seen with forums for particular subject matter, but it only has nature/wildlife and sports. That's more than any other site has but it leaves out some big categories. What I haven't seen anywhere is portraits-- how about a forum for portraits, or just people? Another obvious category would be travel-- or just "places". [Where you live is probably "travel" for me.] Architecture and design would be great too. I'm thinking there's a lot of good work that's not getting shown.