Have found Adult Folio an excellent site to find a good mix of models, amateur and professional for adult style images.

Have meet some very professional photographers and had many great shoots from this site. I only do modelling occasionally now, so being able to apply for a casting when I want to is really useful. The reference system makes it possible to be relaxed and comfortable going to shoot with someone new for the first time, knowing what to expect. The levels listed are always respected. Really have enjoyed my experience here so far!