a.k.a. button exchange
A group of participating Web sites that display each other's ad banners (or buttons) in exchange for credits; the more impressions you display, the more credits you receive. The credits are then converted into ad spaces for you to display your ad banner on participating Web sites. Participating in banner exchange programs is a great way to drive traffic to your site if you have compelling content and a creative ad banner.
NetLingo Classification: Online Marketing