There's this Runescape forum, Zybez/Runescapecommunity, that I joined 5 years ago, but since it's been about 4 years since I've played Runescape I've only been in their Off Topic section since.
There's also an offshoot of this Runescape forum; at a certain point the admin went insane and closed OT, causing the OT regulars to break away and go to an ex-mod's own forum, iPengo. Wasn't one of the original OT regulars, but I joined iPengo not much later and I've been there since.
And lastly, there's this Dutch girls' forum, an offshoot of the Fancy (= girls' magazine) forums with a similar political drama, that I occasionally lurk. I was introduced by a classmate, even though she's not there anymore and the only other really interesting person there I've lost most contact with. They're a very xenophobic (in the "we don't like new people" sense) and clique-oriented lot, which makes for some heavy argumentation that even the hottest topics of OT can't equal.