I frequent
www.tidesofblood.com - However they are a bit internal, I guess. Tides of Blood (or ToB) is a WarCraft 3 custom map, so most of the forum is about ToB, WC3 and mapmaking. However, the general discussion area (The fast and the spurious, it's called) and the political area (the bloody stump) are interesting at times. The forums are dominated by americans, so there's no use getting heavily into their political discussions (atleast not for me).
That being said, I don't think there's much point in going there unless you actually play the game - but I might be wrong, as I've never tried otherwise ;-) It's a bit hard to get into the community if you don't play, is what I'm saying. Also, most of the posters are underage (or seem so), and there's a lot of bitching and aggresive behaviour there