Can I start clicking like crazy on a link in the search results and rank it higher than it is currently? A Search Engine Watch Forums thread addresses this question.
If a large number of people did a search for a specific key phrase and kept clicking on a result that appeared in page 4, for a certain period of time, could it cause the site to move up in the Google results? maybe increase PR?
Forum members suspect that it could have an impact but it probably won't be used heavily because of the possible manipulation.
Some people believe usage data will eventually become as important as link authority..or at least be a strong 2nd factor. What's gonna happen nobody knows for sure, but I've also read opinions, that it won't become the most important factor, as it's just too easy to manipulate (the way you suggested for example :-)). I think letting the users judge through their actions could be a great way to improve an engine's algorithm, but if it should really be too prone to manipulation, they probably can't depend on it too much.
It is also something that one of our editors, evilgreenmonkey, plans to do a study on, because, after all, he says: "Google's click tracking on natural search results is there for a reason, and it would a sensible assumption that CTR can alter your ranking."
I had Personalized Search enabled for a short time this weekend, and as I clicked on the results for a specific search term, it started counting the number of visits I had made and moved the specific result from the #2 spot to the #1 spot under the personalized engine. So there was a definite emphasis on clickthroughs as a ranking mechanism under Personalized Search.
The question is, does Google use click data for the search results for searches performed when a user is not logged in?
On a similar note, back when the Direct Hit search engine existed, it utilized click data to rank sites. However, due to the manipulation, it was made extinct. Recently, it was mentioned that the Ask.com algorithm known as Edison will be bringing part of this feature back to some extent: "In a sense, it uses the 'wisdom of the crowds' to determine relevancy and show the best results they can."
Forum discussion continues at Search Engine Watch Forums.