Faceted Search on CodePlex

http://www.codeplex.com/FacetedSearch

MOSS Faceted Search is a set of web parts that provide intuitive way to refine search results by category (facet).
The facets are implemented using SharePoint API and stored within native SharePoint METADATA store. The solution demonstrates following key features:

• Grouping search results by facet
• Displaying a total number of hits per facet value
• Refining search results by facet value
• Update of the facet menu based on refined search criteria
• Displaying of the search criteria in a Bread Crumbs
• Ability to exclude the chosen facet from the search criteria
• Flexibility of the Faceted search configuration and its consistency with MOSS administration