Have you seen this?
Log into your Google account, then do a web search. Adjacent to each returned URL are new icons, an up arrow and an X, with a talk balloon below. Clicking the arrow "promotes" the result, literally moving it to the top of the page. Clicking the X "demotes" it, hiding it from view. The balloon opens a text box where you can record comments about the site.
There is also an "Add a Result" link on each page, for adding URLs missing from the results you think are worthy.
These actions are persistent and will alter the search results accordingly every time you use the same search terms (as long as you're logged in).
At the bottom of the page is a "See All Notes for This SearchWiki" link. That will raise a page of all the results that have either been promoted/demoted or commented on by any user. It is in effect, a community ranking for sites returned in searches.
I don't know what I think of this yet, it seems kind of cumbersome. And injecting community ranking into web searches just seems like an opportunity for partisan warfare and pollution, I don't know how useful it can be (just wait until this site starts amassing votes/comments and the calls go out to save it from "freeping").
It's an interesting idea though, whether it winds up working or not. Those guys at Google are always up to something.
http://www.google.com/support/websearch/bin/answer.py?hl=en&answer=115764