Google Adsensehelp Tutorial:
9. Affiliate Marketing and Google Adsense

The advent of Google Adsense has meant that the web site owner no longer necessarily needs to choose and recommend particular products in order to run a profitable web site. However, it is wise not to become over dependent on any one income source and combining Google Adsense with Affiliate Marketing makes sense as it provides another possible revenue stream. (Affiliate Marketing is the process of linking to other products or services; a commission being paid to us if a sale is made.) For a discussion of Affiliate Marketing, you might like to try  site: affiliatee.com.