Ad Swapping. What Is It?

http://adswapping.net - free ebook to download from the web site.
Ad swapping is exactly what it says on the tin, it is the swapping of adverts with other publishers. So you advertise in their newsletter and they advertise in yours. You advertise on their web site, they advertise on yours. Some people even swap ads in ebooks, although ads on newsletters are by far the most popular.