This search tool from Vivísimo offers clustered results for a selection of searches. Metasearch the whole web, or use tabs to search for news, gossip, images, or products. Options to search Wikipedia, blogs and Slashdot... Clusty

Features results from Google with Alexa details added, plus Amazon book search in a separate column. Additional options - images, movies and reference - can be selected. Users can log in to retain search history and individual preferences. Also offers a toolbar... A9.com

Article in the online collaborative encyclopedia, describing the history and mechanisms of Web search engines. Basically it's a well detailed explanation of what search engine actually is... Wikipedia: Search Engine

Offers 180+ vertical search sites, each on its own domain. Content from its own web search, FindArticles and Furl, with related news provided by Topix. Company profile and information for searchers, publishers and advertisers... LookSmart

Offers web results from Google, combined with multimedia and other content from AOL and various partners. Plus dedicated search tools for video, audio, news and local information... AOL Search

Search tool owned by Yahoo and using its database, but presenting results differently. Also offers news, picture, video, and audio search... AllTheWeb

About.com: expert guidance from real people searching the Internet for the information, goods, and services that you need to know related to your passion... About.com

Offers search for web sites, images, news, blogs, video, maps and directions, local search and shopping... Ask.com

Microsoft provides search of the web, news, images and its own encyclopedia, Encarta. Also offers desktop search via a toolbar... Live Search

The first large scale directory of the Internet, now a major portal offering search engine results, customizable content, chatrooms, free e-mail, clubs, and pager... Yahoo!