App marketplace Appia today launched a new performance based advertising network for app developers. The service is launching today at the 2011 AppNation conference in San Francisco as a “pay per download” opportunity.

Appia’s new ad network enables developers to promote their apps by targeting ads by country and platform to promote their apps; it supports Android, iOS, Java, Symbian, Windows Mobile, BlackBerry, and Palm; and developers only pay for actual downloads of their apps.

“While developers scramble to figure out discoverability in light of new policies within Apple’s App Store and Google’s Android Marketplace, we are providing new options for developers to market and promote their apps and only pay for results,” said Jud Bowman, founder and CEO, Appia. “Our performance-based advertising network gives developers a powerful way to directly influence the placement and traffic of their apps, leading to greater discoverability and increased downloads.”

Appia delivered 22 million downloads in March, reaching over 200 million mobile subscribers in 200 countries.