[Updated 3/31/2007] This is my official advertising polcy. I use advertising from several sources, mostly affiliate programs.
For the affiliate programs, I only advertise from those merchants that I personally have used. Links to those merchants are on the right hand column. I may also put links in my posts to those merchants where they can apply and I may make posts about special deals those merchants might make.
Amazon is one of the affiliate programs I use. They have a context links program which will automatically scan my site and add links to products. These links are differentiated from normal links by being orange. These links do not show up on RSS feeds.
Finally, I used Google Adsense. These links should be clearly marked.