Clustering search engines: a review
Xerox was one of the first companies to work on clustering services in the early 2000’s, in their Research center in Grenoble (France).
Many changes happened since then, in the clustering search services: Kartoo, among others, has disappeared.
The authors gives here a good overview of current systems which may allow you to try a more efficient search on the web.
Youngkin, Andrew. Clustering search strategies: an overview and update. FUMSI, September 2010. Online: