I think there is still a misconception here that one free download equals one lost sale. It doesn't. 
That doesn't excuse copyright infringement, but the concept must be clear. The person who downloads your book would not necessarily have bought it in other circumstances. That's point one.
Point two is, when someone said above that books have no publishing costs, they were clearly wrong. However, they were just as clearly pointing out that in comparison to a hardcover book, the publishing overheads of an book are vastly less than those of a hardcopy book, unless you have some magical deals with printers, typesetting, paper suppliers,bookbinding, transport, warehousing and distribution. Come on, don't cheapen yourself with petty hairsplitting and deliberate failures to contextually interpret people who bother to comment.
Third point, the idea of contacting advertisers is a good one, but don't bother contacting the people selling the advertised products. Unsteady, get in touch with the Google awards team as well as people like commission junction and the suppliers of advertising.