I just got off the phone with someone that sells web analytic services. He has a great and free way to get his advertisement out. - yes, I asked him if I could post this. He said not to mention his site or name. He posts an email address on his website using a simple mailto: link. All sorts of web marketers grab the email address and send this particular email address spam. The trick is, he has an autoresponder set up. Every time someone sends him spam, his autoresponder replies with his ad. Since this email address only recieves spam, he auto deletes all incoming emails. No maintenence once set up. It has only resulted in a few sales a month but considering it takes ten minutes to set up, it's not a bad idea.
He mentioned that 98% of his emails are probably trashed without being seen. However, it still gets some results. His website has huge traffic and he has a webmaster related product. It may work for him for those reasons. Although I think it is an interesting idea, I'm not going to employ it. I don't think spamming marketers are my target market.