We're looking at starting an affiliate program where X number of products sold gets a free product for the affiliate. At its simplest, we just need to have it so people can sign up and get an affiliate code, grab links/banners, and then be able to keep track of their sales so we can manually give them a discount coupon when they sell X products.

So it sounds like there would need to be some kind of feature added to have the affiliate program optionally based on # of products sold rather than amount of sale. If you're accepting bounties for features like this, can you let me know what kind of donation you'd be looking for?