just found this in seomoz.com today http://linkbucks.com/ You will get paid when a user leave you site by click a link on your site. If i didn't understand wrong, this is how it work. When a user click on link on your site, the new page open in a bottom frame. The top frame will be a banner ads by linkbucks second is Intermission. Whenever a user click a link, a page of advertisment show up. You will have to click "continue" to go to the site you wanted to go. I doubt most web user know it is your site playing trick. They are going to blame the page that they are going to. What do you think about linkbuck?
If you want to see LinkBucks in action, I have examples of the links here: http://www.admoolah.com/blog/index.php/2006/11/linkbucks-new-advertising-network/ The more I think about this service, with the low payout and the annoyance to the user, the less I like it.