Twigkit
TwigKit is an easy-to-use toolkit that enables any web designer to quickly build full-featured search applications that look and feel great.
TwigKit automatically produces valid, semantically consistent XHTML, carefully crafted for comprehensive CSS support out of the box. TwigKit is search engine agnostic. That means it's compatible with many enterprise search engines such as FAST ESP and Solr. But, more importantly, it means that you can change search engines without having to rewrite your application.