Metasearch Engines
Clusty is an example of a metasearch engine.
Metasearch engines search the databases of several search engines at a time (e.g., Looksmart, Gigablast, Lycos, etc).
Most eliminate duplicate listings.
Usually, you have little control over search options.
Best for an overview of your topic on the Web, seeing which search engines will produce the best results, and for simple searches.
Sometimes metasearch engines won't be very thorough and don't always include major search engines (like Google).
Other metasearch engines: Dogpile, MetaCrawler, and Search.