I use free advertising all the time. It pays off a lot better than paid advertising. Unless you have thousands to do so.
Unless your keywords have little competition and you rank high in a short amount of time, there is no free promotion. You have to choose from: - paid promotion, - free promotion (but you use your time - actually it is not free, because your time means money). You have to find the balance. Act wise and make money.
adwords does work and does bring tons of traffic. much more than i could ever get from natural search. it just costs a fortune with no guaranteed results.
I have to agree 100% I love to do both. If i am getting a good ROI from the traffic it doesn't matter if its free or paid.