Amazon.com has a program called the Amazon Honor System. They developed this as a way for small websites to receive a monetary donation from $1 - $50 from Amazon.com members.
It's a great way for a smaller website to be commercial free.
For more information, visit Amazon:
http://s1.amazon.com/exec/varzea/subst/fx/help/how-we-know.html/058-1442697-8725433
