Kereia's wonderful Buffy/Spike fanfic and lots more
Of Muses and Minions
Spikelicious' and Larissa's Spike/Buffy fanfic
Organized Insanity: Crazy Evil Dru's site
Rebecca's Buffy and Roswell site
OzMIA: Home of all things Oz, especially Oz/Willow.
Path Less Traveled
Ciderbreak's Willow/Angel fanfic.
Not fanfic per se, but hilarious.
Promised and Chosen
Heavily under construction, but the notes are hilarious. Will someday be a Buffy/Doyle site.
Home of Noctiluca's and Luna's Sites, loads of Spike.