There's a new search engine called Mooter that works differently from the others. Its search results display in a cluster with the main search term in the center and related clusters on spokes branching from it. As you examine each of the clusters, the search results re-order themselves based on your selections. It tries to return the most relevant results by "learning" what you find useful. Take a look at the Mooter company site for more info on how it works.
As Spock would say,"Fascinating."