A few years ago I heard that Google had Pay Per Action Ads. This is the link (services.google.com/payperaction) but it is broken. Why did they stop offering this service? I believe people would prefer more to pay when someone actually buys something from them or subscribes to their service than to pay for silly clicks from people who mostly don't purchase anything and waste their money? I think that Google found out that it is better to milk the advertisers by charging them per click than to charge them per action. This just shows you how many people are losing money using PPC, because if Pay Per Action Ads brought more money to Google, why would they cancel them?
I think they have changed the url to http://www.connectcommerce.com I have an account and a few months ago they let me know . try and see if that what you are looking for.
That page says Google Affiliate Network. Am I missing something? What do you do on that page? It doesn't look like any Pay Per Action Ads system or anything to do with pay per action.