Just in case you didn't hear yesterday, Google Adwords now has a pay per action beta test going on:

"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://adwords.blogspot.com/2007/03/...beta-test.html