There's alot of micro community sites in the horror genre. Do you have any unique angles / compelling content in mind?
What do you do in adult? Zombie babe of the month can always be a good add. You wouldn't be the only site doing it, but it's a start. It's something that attracts a male base, team up with a company like sideshow collectables or house of mysterious secrets and offer some gift certificates so you have a value add and start inviting hot undead girls on facebook to compete - you get content as well as free advertizing and traffic.
Oh, and Billy Mitchell sucks.
Steve Weibe 4 Lyfe!