Brat has a couple that might interest you:
Choices by Brat
Summary: Buffy is NOT the Chosen One. She is a girl with Powers and Spike and Angel are her protectors. (B/S/A)
You Mean the World to Me by BratSummary: AU: Buffy is not the Slayer, but a girl with powers. Spike is her vampire with a soul protector. He's just claimed her and she is NOT happy about it.
(available at Nocturnal Light)
And for something silly, how about
TammyAsh666's "The Adventures of Porn Girl"?
Summary: Buffy Summers is just a normal girl by day, Porn Girl by night, your not so average superhero. For months she has tried to catch Spike, her arch nemesis, but he always manages to slip away. What happens when they do cross paths, both with an obvious attraction to the other? Will Porn Girl give in to her lusty feelings, or lock him up like the criminal he is?