Judging by the posts it seems to appear that cash is the winner.

Does anyone have a formula? How much per number of leads or number of sales? Just wondering what has been tried and tested out there.

Also, I did hear from a dinner table conversation from a top marketer that he likes to surprise his top affiliates in a launch with a fancy plaque or laser engraved crystal trophy in addition to the cash prize he send them. This is totally unannounced and the affiliates are delighted to get behind his promotions the next time.

Seems like a nice touch to go "above and beyond" although I'm not sure how many people are actually using this affiliate motivation technique.