I find the design nice and clean, the surfer knows right away where he arrived and it's outlining the main sale points with well picked visuals.
However - here's my
or perhaps more like some food for thought:
a) the sequence of the buttons in the upper menu - according to my experience this can majorly influence the sales, In general your goal is to demonstrate as much value as possible and ideally in the right order, so the final touch tfter one tours the site works as a dealbraker.
I'm sure you keep an overview of where people click the most, or where they head most often right after they hit the home page
b) My guess it could be be "the models"
So perhaps, you may want to gauge which models are clicked on the most, showcasing them at the top and perhaps also consider A/B testing a little teaser, which can be as simple as a few small preview pictures or outlining how much content is available in the member area with each particular model.
The same way you may want to check where people leave or tend to spend the most time without submitting the join page and then leave elsewhere.
c) Deeplinking to the models - may make sense too although I'm sure you thought about this and perhaps target models with your promo materials already.
d) Doublecheck if the surfer universally gets what all is included in the membership - I believe the sequence of buttons makes a universal sense now altough my initial surfer's feel is that "Livecams" and "DVD's" are something extra not included in my membership.
The benefits list on the right lists all those but it's still not crystal clear whether it's really included. Perhaps you may even consider calling the DVD's button a "Bonus" instead or even add a showcase of other specials that are a part of the membership to the mix - everyone likes to get something extra with his order.
If I click on the "Live models" and "DVD's" links it's again mentioned that these are included - but I would make it stand out more at the homepage itself. Perhaps even repeat and put the offer in a little more detail at the bottom of the homepage with a join link below it.
e) Also perhaps consider making the text at the join page a little bit more persuasive so it's clear that all the features are really included in the membership one's buying
P.S. the livecam plugs don't work with me atm so maybe I've adressed something that can be included in their presentation.
All in all this is a teen super site that deserves domination so I wish the best and hope that any part of the feedback can be of some use.