Buffy the Vampire Slayer/Firefly
A Friend to the Spirit by ChronicBookworm
River dreams of an angel, a girl like her. Gen.
Xena: Warrior Princess/Legend of the Seeker
Commanded by shopfront
Cara sets off to get Xena in line for Lord Rahl. F/F.
Fulcrum: The forgotten files by Whenhopediesyoung
A series of peeks at Ahsoka's life in a Kingsman fusion. I've never watched the Kingsman movies, but this was delightful and sad. F/F.
Buffy the Vampire Slayer/Star Wars
Ahsoka the Vampire Slayer by Redrikki
A BTVS/SW fusion, wherein Ahsoka must contend with the worries of her Watcher and the presence of a new Slayer. Gen.
The Golden Girls/The Purge
The Funny Pit by Missy
The Purge fusion AU, in which the girls wait for Blanche. Gen.
Buffy the Vampire Slayer
Someone to Save by ChronicBookworm
Buffy goes back in time to save the world only to find she's arrived earlier than intended, with all the opportunities that brings. Buffy/Kendra.
silk ribbons by Snickfic
Drusilla, Faith, and a corset. F/F.
blurring the lines by kwritten
Buffy slips between worlds. AU where Tara lives. F/F.
flying by verity
Buffy, Willow, and dreams. Between seasons six and seven. Gen.
Five Summers That Never Were by Alixtii
A series of double drabbles, featuring Buffy and women I'd have loved her to fuck. F/F.
five things Tara forgot by gogollescent
Five scenes we didn't see. A Tara character study. F/F.
City Girls by Selena
Post-canon. Buffy and Dawn in Rome. Gen.
Cross to Bear by templemarker
Buffy collects crosses. Gen.
the in-between by darlingargents
Missing scene wherein Ahsoka gets a little help between battles.
Along Our Twisted Path by ambiguously
Ahsoka walks out of one dimension and into one that's familiar, but not quite the same. F/M.
Penumbra by buppypotato
Barriss is a mess. F/F.
Aphelion by buppypotato
In a universe where Sidious was stopped earlier, Ahsoka still needs to find herself post-Jedi Order. F/M/F.
flow in a perfect gale by kimaracretak
Sabine, Ahsoka, and sabers.
The Haunting of Hill House by Shirley Jackson
i come with tbe breath of the dead by kimaracretak
A woman, the house that loves her, and the woman who comes back. F/F.
Once Upon a Time in Wonderland
Encounter Darkness by Trobadora
Post-series. Anastasia pays the Jabberwocky a visit. F/F.
Bonus Site Rec:
When I entered Buffy fandom a few years late in 2005--back in the time when character archives were chugging along, right at the dawn of LJ--this was one of the first sites I knew and loved.
Blood and Honey - Buffy Summers Fanfiction Archive