Chats and Forums
All LotR Fic, Anything Goes at the Council of the Ring, Aragorn Arwen, Bag End, Beyond Middle Earth, Boromir Fanfiction, Elrond's Slaves, Haldir's Whores, Lord of the Rings Discipline, Lord of the Rings Fanfiction
Slash
Character, Chats and Forums, Real-Person, Chocolate Dipped Hobbit, Fellowslash, Four Hobbits, Lanna's Cûningerin, Laurelindórenan, Minya Andúnë, Secret Panel: LOTR, Sweet As Sin: Lord of the Rings Slashfiction, The Lure of the Ring, Vera's Dreamscape
Ansereg
Slash, het, BDSM, and dark stories by Tyellas. Features the Elladan/Elrohir pairing.
Boromir: A Hero's Journey
Dedicated to the character of Boromir as portrayed by Sean Bean in the movie. Has stories of all types, and a large image collection.
FanFiction.Net: Lord of the Rings
Stories by many authors, of all ratings except NC-17, and in all genres except real-person. Many writers post their first stories here.
Haven Sent
A! Elbereth's site on Frodo Baggins, with slash and gen fanfiction stories and icons.
Incandescent
Het and slash fiction, art, photo manipulations, and comics by Trinity Helix.
Open Scrolls Archive
Het stories by various authors, in an archive maintained by ScribeOz and Dolarabee.
Other People's Stories
Mary Borsellino's character stories, including the Rosie/Sam/Frodo series Pretty Good Year.
Parma Eruseen
General fan fiction archive and forum, featuring many characters and pairings by multiple authors.
Temple of Gutter: LotR
Character stories by various authors, categorised by species.
The Fellowship of the Legolas
Stories and artwork featuring the character of Legolas.