These companies (Google, Yahoo, Microsoft and others) let the user to rank the result of search, but I think the way they uses is completely “brain damage”.
When you do a search on Google for example it will list a number of sites and the phrase in this site with texts related to your searched words. For each result you have the “Promote” and “Remove” button, but how can I promote it if I didn’t read the problem content of that site?
I think a better idea could be using a footnote (obviously at bottom of page) of visited web site where the user could to define your opinion. Nobody like page headers with Ads or anything, but I think using this pool at bottom of page will not bother.
Just my 2 cents, I hope someone from these companies see this comment and think about this idea.