Well, I do know that Fightnews.com has plenty of DWF's on it and you can post from Facebook. It's boxing only though and I don't know of any as far as football. I stay away from those.
A really good one, loaded with DWFs, is Scott Wrights NFL DraftCountdown. As long as you aren't blatant with race accusations, you can pretty much get away with anything. I take pride in my negative "reputation"!
http://www.finheaven.com/forums/index.php is the DWF forum that usually frequent to talk Dolphins football with other Fins fans. Of course, they called me a racist the moment I mentioned that our team should bring in more white defensive lineman like we had during the Don Shula years. Its funny how oblivious these Dolfan DWF's are to the truth, but they know good and well what a kick ass team we had during those years when our team was mostly white.
EDIT: I misread the OP that said DWF boards not directed to one specific team. But in reality though, Finheaven is the only other football board I visit other than Caste Football of course
philaphans.com has mb's devoted to each of the big 4 Phila. teams. I sometimes go there but can't remember the last time I posted on there.
Also, try the506.com/yabb . When you get there, click "here", and it'll bring up the login page (you have to register to see the boards on that site). I post on there occasionally, although I avoid racial issues. I've actually pitched that site on CF in the past.