In mainstream, one moneymaking model involves buying and selling links via REVIEWS. Sites like ReviewMe.com and SponsoredReviews.Com let advertisers find niche-specific blogs where their links will appear in a review. Bloggers make money posting/writing the reviews.
Given the TONS of adult blogs out there, does this service exist in adult? If it doesn't, here's your free adult business idea of the day.
ONE THING TO CONSIDER: Google hates paid links so don't set up your system in such a way that you end up like izea.com's payperpost.com or smorty.com.
Anyway, if you need more ideas to fully flesh this out, hit me up on ICQ. Free brainstorming cuz it's easier to square a number working together than thinking apart
Related topic: Read up on how
THEMED LINKS work