Kowabunga! released some findings recently from a two week test utilizing an automated image feed from Image Advantage.
Based on their observations, the process of matching images to ads generated significant gains for affiliates from the start.
Here is an example of the automated image feed in action from the bottom of an mpire.com page.
Kowabunga! currently provides Image Advantage as part of its ValidClick Search Network but may also incorporate the service into other solutions.
More details at http://www.kowabunga.com/kowabunga-press-release.aspx?id=300.