Fanfic Sites

[Inkstained Fingers] - HUGE archive of every Harry Potter slash pairing imaginable.  You will need to apply for a password to access the stories.

[ETC: Evil Twin Corp] - A combination of three archives (Beloved Enemies, After Class, Canis Major) which are dedicated to three pairings respectively: Harry/Lucius, Harry/Snape, and Harry/Sirius.  There aren't many stories up yet, but it is a quickly growing community.  Here you can also find Hogwarts: A Rehabilitated History which is: "... not an RPG, but a shared universe created by a group of horny insane fanfic writers."

[Harry Potter Rareslash Archive] - Is exactly what it sounds like, an archive dedicated to the rarer HP slash pairings such as: Harry/Cedric, Oliver/Ron, Dudley/Harry, etc.

[Walking the Plank] - A Harry/Snape archive.

[Skyehawke] - Another large archive of HP slash which includes NC-17 rated stories.

[FictionAlley.org] - Yet another HUGE archive of stories which include gen, het and slash.  All ratings.

[Graymarye] - Slash archive organized by pairing.

[Potter Slash Archive] - An archive for slash involving the Potter family.

[Pure Magnetism] - A Harry/Draco slash archive.

[Restricted Section] - An archive of NC-17 fics, both slash and het.

[Switchknife's Slash Recommendations] - Fairly large archive of slash recs, sites, and archives organized by pairing.

[The Severus Snape Fuh-Q-Fest] - Snape slash challenges and responses.

[The Harry Potter/Severus Snape Fuh-Q-Fest] - Harry/Snape slash challenges and responses.

 

General HP sites

[Snape's Dungeon] - A great Snape site with a huge archive of pictures and screencaps from the movies, definitely worth checking out.  Some of the site isn't in English, but it is still very easy to navigate.

[The Harry Potter Lexicon] - Everyone knows this one, a huge resource of Harry Potter facts organized into categories (characters, places, things, spells, creatures, etc.).

[The Greasy Git] - Good site for info, images, links and updates on Alan Rickman and the character of Severus Snape.  The site also includes updates on the movies and books.

[The Leaky Cauldron] - HUGE resource for news updates concerning the movies and the books that is updated daily.  Also includes galleries, quotes, and other Harry Potter goodies :)

[The Snitch.co.uk] - This site concentrates mostly on the movie and has a huge archives of pictures as well as a news, downloads, fonts, and an interactive community.

[Daniel Radcliffe: Mystical Wonder] - Expansive media section with lots of downloadable clips.

[Mugglenet.com] - Lots of stuff.  Lots and lots of stuff.

[Aquiline] - Alan Rickman fanlisting site with a huge archive of pictures from his various movie roles.

[DanRadcliffe.co.uk] - Wonderful Daniel Radcliffe fansite with lots of fun stuff and information, definitely check out their 'downloads' section.