Interesting that there are so few responses.

Over at http://blogsetup.com , I set up Post Affiliate Pro with some custom PHP code to integrate it so the commission triggers upon fill out of a form, then goes into a "Pending" state until we manually verify it. Post Affiliate Pro is pretty flexible and has a good API for this kind of stuff.

I also looked at iDevAffiliate, but ultimately picked Post Affiliate Pro because it has better SEO on the links and, in general, it had better reviews. The general class of software you are looking for is "affiliate software".