... and you're looking for a network that promotes 2 tier affiliate programs, correct?
That leaves out Clickbank and PayDotCom, if you want the process to be automated through their system ... you'll have to either use an affiliate module/affiliate software that tracks multiple tiers and have the merchant pay you manually in that case.
Or you can find merchants and/or complete Networks that are actually offering 2 Tier programs and have all the tracking and processing in house.
I'd also like to make it clear that working in this capacity is far from easy ... it's actually more difficult than promoting as an affiliate on the 1st Tier, IMHO.
... but that's for me to know, and you to find out.