The programs that make the most cash are the ones that REBILL the customers every month. While paid-per-lead may sound enticing on a short term, long term results end up being far more successful with a rebilling program.
Essentially, cam sites, dating sites, membership sites and casinos is where it's at. Long term profit vs. short term burst.
Think about it... If you get paid per lead, that's because that company knows they can spend X amount of dollars per lead since 1 in 30 leads will convert. Something like that. The point is, that company is making more money than you from the customer that you just did all the work to get. With RevShare programs, you make 50% of the life of the account. That can amount to HUGE sums in the long run. If a client is willing to pay per lead, you would definitely make more getting paid with rev share. A repeat paying customer is worth gold.