APIHut is an experimental faceted search engine. As its name suggests, it was originally meant to be a faceted search engine for RESTful Web APIs. The current version is a generic document indexing and faceted search engine, not limited to the use of Web APIs.
APIHut : Version 1
More details and publications available at the original APIHut page.
APIHut : Version 2 (a.k.a Kino)
This is a rewritten version of APIHut called Kino, uses Apache SOLR and a flexible intermediate application with Ajax capability. More details are avaialble at the Kino details page.