[nekrom]

Decent members areas with 3 months as an average rebilling per member
Upsells
Cross sells
Email sales from tour page collection
Re-selling exclusive content they may produce for their paysites
Selling exit traffic
Console sales that aren't passed onto the affiliates
Dialer/ach/sms/alternative cc sales ie: (jcb) that aren't passed onto the affiliate

And I'm sure many other methods that aren't listed here.

-N