Cybersexnetwork and
Cyberage both do this. They have great tour pages which actually converts very good. I am usually making a site with content then letting the tour pages make the signup and they work great.
Just a note; using a well known avs system is not a good idea, because many of the surfers will probably have seen or sign up with it before, try a brand new quality avs system, hmmm , like the one in my signature
