Attractive Open Source Search Interfaces?

An anonymous reader writes "I work for a company that manages an online database for the political market. We add to this DB daily with updates from a variety of sources and our customers then search through this content via our Solr/Lucene search engine. My problem is, our search interface is a little, well, basic and I would love to know if there are any feature-rich open source alternatives out there. The only one I can find is Flamenco, and while that seems strong on categorisation, that seems to be about the height of it."