Actually, most dating sites fit into that category.
The best way, however is to learn to pickup women online.
Are you looking for an adult dating site that caters to adult encounters or casual sex, that isn't full of scammers or fake profiles?
If that's the case, I'll admit it's pretty hard to find.
These sites have plenty of pretty women on them, all looking for relationships.
Anyway, you’re unlikely to meet a woman at a church, a bar, a club, the arcade, or your Mom’s basement.