Jakob Nielsen has posted a short article you should read about the importance of converting search engine advertising traffic: Search Engines as Leeches on the Web.
Search engines extract too much of the Web’s value, leaving too little for the websites that actually create the content. Liberation from search dependency is a strategic imperative for both websites and software vendors.
Worth a read if you are using advertising on search engines to drive traffic to your web site.
C. David Gammel, CAE 
I like his suggestions for more direct interaction with consumers – a good summary of options. But isn’t it kind of silly to suggest that Google is hurting companies? The 1st part of the article is pretty disingenuous if you ask me (you didn’t, sorry). Homey says “the companies” pay for the content and we thieving consumers are getting a free ride. Whateva. My thinking is that most of the web’s useful content is put up by individuals, nonprofits or the government — companies put up useful information as an arms-length transaction to gain new clients. It is what it is.
Nielsen has made a career of being over the top, hasn’t he? I agree that search engines are good and need to make money somehow. The current models of paid advertising are not too intrusive. I do think, as you agree, his suggestions on how to retain traffic to reduce reliance on search-sourced traffic are worth exploring.