AFF.N: This is an adult Fanfiction page with many different fandoms.
The Rift: This is Knight Smeg's site it has different fandoms as well and she's an awesome author. So go check this place out!
Weasleys Wizard Wheezes: This place also run by Knight Smeg. If all you want is Fred/George center fics you can see them here paired off with many people. Also has fan art.
Restricted Section: Great place to go if your only looking for NC17 special pairings.
A Family Affair: The greatest Weasley incest arcive out there. Go check it out if incest doesn't sqick you.
The Burrow: Another Weasley incest arcive. Good stories too.
Nut Fiction: Nice fanfiction site just created recently so it doesn't have alot. But still its good none the less.
The Potter Slash Arcive: Great fic site but sorry if you want the NC17 stories you need to join the group and ask how to get them.
The Malfoy Slash Arcive: Another great fic site but these stories are based on the Malfoy family insted of Harry Potter.