Has anyone heard of Pay Per Play Audio Ads by Netaudioads? I just signed up to monetize my websites, however, they are not launching until February 2008. I think they will give adsense a run for its money. As a publisher, you will get paid for every visitor that comes to your site. A 5sec audio ad related to your content will play once for the visitor and that is it. 100% conversion and you know exactly how much you getting paid from what the advertiser pays. It will be modeled after adsense on the bidding system.
To find out more visit the site: www.sellingppp.com