Stardestroyer.net fits that description somewhat, for values of "casually" that allow for copious swearing punctuating most disagreements. I haven't posted there, but Kaj Sotala posts as Xuenay (apologies no apologies for stalking).
Examples of threads on LW-related topics:
(Edited after first upvote; later edited again to add a link.)
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.