off the top of my head, I can think of two using it
www.boobdollars.com
www.porndaddy.net
Pros: Nice cascading billing, Gallery of the Day built into stats
Cons: MPA2 has a built in "shave option" for only $50/month more!
Seen both sites above turn into binary garbage at least once, instead of the regular html page, and had to inform the webmasters to get them to fix it.
ZoiNk