With the recent changes in Associates program, Amazon no longer pay referral fees to Associates who send users to to Amazon websites through keyword bidding and other paid search on search engines. “As of May 1, 2009, Associates will not be paid referral fees for paid search traffic.  Also, in connection with this change, as of May 1, 2009, Amazon will no longer make data feeds available to Associates for the purpose of sending users to the Amazon websites in the US or Canada via paid search. FAQ”