Adult Domain Names

I think the best thing is to create a website or blog where you can talk about it and sell the domain name as well.

There's several forums that specifically target the adult hosting niche, they'd be a good place to start.

I agree, forums are the best. There's also an adult section on ebay that they make hard to find (google "ebay adult section"). I sold a few in there, but buyers on there are few and few between. It's just a last resort type of thing.

Forums or creating your own website would be the best solution. Start with forums in my opinion.