Well, I've got one, hentaikid.com - 100% exclusive content you can sign up as an affiliate
here
I can give you some free content to promote it
then there's
http://www.gregboone.com/
http://crazyxxx3dworld.com
http://mmganime.com has exclusive content but the affiliate system doesn't seem to be up yet
There are lots of small artist run paysites but most don't have affiliate systems: sendouya.com, orgymania.net, karstensadultart.com, jaxtrawstudios.com etc...