Amazon have started beta testing a new feature with their affiliates that is something between Chitika’s eMiniMalls and Vibrant Media’s Intellitxt. It’s called Amazon Product Previews.
The window disappears when you take the cursor away.
During the beta test only 50% of readers to sites testing the feature will see the ads – it’s some kind of controlled test.
To participate in the program you just need to be an Amazon affiliate as far as I can see – log into the associate’s page and you should be invited to join the beta test.