We've just finished up adding them as an ad type to our FREE
www.madisonavenue.com Ad Rotation Solution so you can rotate in anyone you want with these types of ads. We do the same thing for Page Peel ads, floating ads, banners, and two types of text links.
Don't get trapped promoting only one sponsor because they're providing you the code to run the ad. Use us, rotate in anyone you want, AND use a kick-ass technology to determine which sponsor programs and sites are generating you the highest RPM (revenue / 1000 impressions).