With all xxx websites, and not only, you can't forget about a fully fledged mobile version of the site. There is no way to stay in the business, in a long term perspective, without working with websites like
Bitter Strawberry, and
Sex Goes Mobile. Mobile popunders from
Plugrush are good part of the equation too.
Other ad networks to consider are
First Mobile Cash, and
VPS Mobile, which may turn out to be even more profitable, then the mix above.