Via Seth Godin, here’s an article on Search Engine Watch about how users evaluate the Google search results page. They conducted of (only) 50 users to see where they looked in the Google search results.
100% of them looked at the top three results, declining down to 20% looking at the tenth ranked item (the last one on the first page).
This sounds dubious to me, but apparently 50% of searchers look at the top-place ad on the right-hand side of the page. Speaking as a guy who, ironically, runs several of these campaigns for clients, I never, ever look at the ads. It’s probably because I trust Google’s algorithms a lot more than the potentially-ethically-compromised advertisers.
DarrenBarefoot.com 
“I never, ever look at the ads.”
If you said something like “I rarely look at the ads” or “I know the ads are there, and sometimes my eye falls on them, but I’ve never clicked on them”, that type of claim might be more believable. Unless somebody tracked your eye movements as you went down a web page (or even better, tracked your eye movements during a day’s worth of surfing around), I don’t think you–or anyone–can say you’ve “never, ever” looked at ads. My point is you may *think* you don’t look at them, but the chances are pretty good that you are without your realizing it.
I’m referring particularly here to the Google AdWord ads–I wouldn’t make that claim for the Web generally. The dancing monkeys are too flashy to not look at, if only to adblock them.
However, I’m fairly certain when looking at Google results that my eyes never stray to that right-hand column. It may happen subconciously, but I don’t know that I’ve ever clicked on a Google ad–unless it’s because I’m testing some ads.