A search results clustering framework. Includes clustering components and a stand-alone meta search component.

Clusters results from major search engines, associates words that appear in previous searches, and keeps a local cache of all the results you click on in a searchable database. It helps keep track of what you find on the web. [Windows, UNIX, Linux and Mac OSX.]

Grokker clusters Google's results and local files. It uses an interface which visualizes clusters by means of circles.

Grouper partitioned the results into clusters, or groupings of URLs which contain similar content.

The Query Server Web search page queries eight general purpose Web search engines, and returns a single merged, ranked and conceptually clustered list.

A metasearch clustering engine for Web, Books, News

Their document clustering and meta-search software automatically categorizes search results on-the-fly into hierarchical clusters.