I've tried ad words for about a month. Found it too expensive... Some clicks could cost upwards of a dollar! It really hurts when these users promptly leave the site. You can burn through your daily quota quick quickly. Now, if I were to do it again, I would put a little more thought into what ad words I was targetting. I obviously was using some very popular ad words which cost more. I think the trick is to find a smaller ad word 'niche' that can still draw targetted traffic without competing with the most sought after words/phrases.