The Rolling Smut Factory of Epic Proportions - Brenda and Val's site, hosting many, many enjoyable fics. Here you will find some more unusual pairings and wonderful writing.
Secret Panel Fan Fic - Jenwyn's LotR slash, both movieverse and RPS. Great site, great stories. This site also has the archive for her "I Want" challenge. Highly recommended!
Beyond the Fellowship - A terrific site with an equally terrific layout. Lots of pairings by lots of different authors.
DOMinate Me Please! - Elaine's site, where there is much Dom love. I like her series Convolutions and Confusion, wherein you will find an evil!Elijah.
Bloomwood - Stories featuring Elijah and Orlando. Nice layout and great stories.
What It Is - Zarah's site, containing many wonderful LotR RPS stories. It also contains other fandoms (*gasp* they just so happen to be MY other two fandoms, Harry Potter and *NSYNC). She's a great writer, and the site has a lovely layout. A must-visit.
Lure of the Ring - Tricia's site, with her RPS fiction and a beautiful layout.
stories by buffet - A simple site that houses some great fiction, including one of the first LotR RPS series I ever read, fucked. I adore her fiction.
Magical Intrigue - This site houses the fiction (slash and het) of Rhysenn, my favorite Harry Potter slash writer. You can find Irresistible Poison, one of the most popular Harry/Draco series, here. Amazing stuff.
The Potter Slash Archive - Wonderfully organized and designed site that only houses slash involving James and Harry Potter. It includes the work of over 120 authors, so you'll be able to find something there with the Potter of your choice.
Walking the Plank - This site is for Snape/Harry shippers, and I'm telling you, there's some great fiction there by some really terrific authors. They also have fanart.
Till Human Voices Wake Us - Telanu, one of the terrific authors mentioned from Walking the Plank. She has some great Snape/Harry stories up (particularly the Coffee and Tea series), as well as a few Star Wars Obi-Wan/Qui-Gon stories. Okay, so they have nothing to do with HP slash, but they're great stories.
Paper Moon - Aspen's HP slash site rocks. Not only does she have a great design, but her fics are some of the hottest ones I've ever read. This site is great, but not for anyone under 17.
Ivy Blossom's Harry Potter Slash - Ivy Blossom has a beautiful site and a wonderful series on her site, as well as some recs for great stories. The only thing you might beware of is that you don't want to open this page when a lot of people who don't appreciate slash are around. It has some pictures that they might not take to kindly too, and it could be embarassing.
Letters Broken Open - First of all, Kick Flaw is a brilliant writer, and I always enjoy her stories. Also, her site looks nice while still being simple and easy to navigate, which is a definite plus.
Perfectly Flawed - This archive contains purely Draco/Ron slash. Nice, simple design, and some really great fics.
The Slash Page database project - The great thing about this site is that it provides an extensive web of links to sites that house slash of almost any fandom. There are a ton of Harry Potter slash links there, but if you're looking for another fandom, it's pretty likely that you'll be able to find something here.
Experiment V - The home of Rhys' fiction, all of which is pretty damn amazing. Visit it or miss out.
juppy.org - Georgina's lovely site, which includes both *NSYNC and BSB slash. Many lovely stories to be found here, and it's a wonderfully designed site.
Sweet Uncleanness - Matthew is a great writer with a LOT of slash. Here there be *NSYNC, BSB, 98, and even a bit of O-Town slash. Plus he writes in some other fandoms that are rather enjoyable.