Man oh man, sometimes I read a concept that's so up my alley that I want to physically punish myself for not thinking of it first. And this is one of 'em: It's a comic book called Last Blood, and here's the concept: A band of vampires has no choice but to defend the planet's last remaining humans from teeming throngs of zombies.
It makes perfect sense! Without human blood, the vampires would go extinct! So if zombies threaten to eradicate all mankind ... aw, man. It's so simple it's beautiful. The comic book was created by Bobby and Chris Crosby, and the boys are now in the movie business with the comics-lovin' Benderspink Productions. (They also have adaptations of Area 52, Y: The Last Man, and Pet Robots in development at various studios.)