Pay-per-action advertising is a new pricing model that allows you to pay only for completed actions that you define, such as a lead, a sale, or a pageview, after a user has clicked on your ad on a publisher’s site. You’ll define an action, set up conversion tracking, and create ads that publishers in the Google content network can then choose to place in new ad units on their site.

• http://www.google.com/ads/adsense/referrals/index.html

• http://adwords.blogspot.com/2007/03/pay-per-action-beta-test.html