I have a site where I give out daily free tangible-goods (which I buy) to some of the random registered members of my site. As I pay for these free goods from the AD revenue my sites generate. My question is, which AD network (CPM and/or CPC and/or Pop-Under) should I use for my site. I am asking because, it seems out of my research, no AD network allow direct AD revenue sharing with site users. Is there a solution to this problem ?