There's Polish site wykop.pl, it's a digg (now reddit) analogue. They use capped level system (article -> comment -> reply) with special formatting for > quotes and @nicks so people can refer to each other in the comments, and the discussion doesn't differ much in structure from the one on reddit, from what I noticed. It's rather large site, often there's around 300 comments on one article, but it is easy to read (easier than reddit, at least for me).