I can highly recommend Adult Folio. Writing as a photographer it is a great place to arrange castings with a wide variety of models and also a good platform to show case your work. Very importantly the site is easy to use and any queries are swiftly dealt with.

I have to say that joining Adultfolio has been a revelation.
So many amazing models to work with and other like minded photographers.
Thank you James and the team for a brilliantly run site