I don't spend much time in communities. (something I ought to rectify, many are really neat)
My favourites:
westerosorting. It's so much more than a sorting comm. The houses are huge, reasonably active, the tournaments and challenges are interesting, the mods are kooky and fun. It's just a great comm full of wonderful people who love the Song of Ice and Fire books, love/hate/watch and facepalm the show and have a good time doing it.
where_no_woman Star Trek has some amazing women who are often overlooked because the men are equally amazing and there's more of them and everyone wants them to get naked. I wish there were more discussions and meta on here but it's a great place to look for fic and really I'm just happy it exists. It's a really supportive group who like het and femslash and gen, all about the women of Trek, whom I adore.
got-exchange It's a GoT/ASOIAF exchange comm that keeps running one after the other and it's AWESOME. The level of fic and art is superb, it's full of so many different pairings and ideas and no matter what you can think of to ask for, you'll get it and it'll be fantastic. I've never been disappointed by a got-exchange. Usually I'm overwhelmed by quality.
Posted in the mirror verse at
http://oparu.dreamwidth.org/323111.html with
comments.