I have not participated in the poll. My answer will be on how I will advertise, not which advertising I will use.
The reason is firstly I don't have any experience with Google, Yahoo, Bidvertiser etc advertising.
Secondly, it depends on the nature of the product I am offering. For e.g, if I ever start a monitor or HYIP or PTP forum, I'll use other PTP forums to advertise on. In my opinion, that would be the most effective advertising as I will be hitting the potential customers for my product.