Scarlet Thirst by Crin Claxton

Rani is initiated into the vampire lifestyle by the butch dyke Rob and embarks on a hedonistic trip through a sex-fueled underworld to bring more and more women into the life. For once, the lesbian vampire story is not just a metaphor: This novel is as explicit about sex as it is about biting into beautiful young necks. They're butch, they're femme, they're out for blood-and they're tapping the Buffy market with a vengeance.