Exchanging advertisements is an old Internet concept and there are probably more than thirteen years since the first popular advertisement exchange program started.
The concept of exchanging ads, banners, text links and such is still popular with numerous Web services offering all kinds of advertisement exchange programs. The idea of exchanging advertisements is also very noble. Web site owners helping each other to promote their Web sites.
Some advertisement exchange programs focus on niche such as by topic or by type of Web sites. One such is 125exchange.com which is an advertisement exchange program for bloggers. The ratio is 3:2 meaning for every 3 impressions you generate you will get 2 free ad impressions in exchange. At the time of visit there is free impressions just to start.