Zilverline is a search engine that you can use for your files (or for your intranet, as I’m doing). It uses Lucene under the covers. I found it quite easy to set up. If you know Lucene query syntax, you can get very good search results. I’ve passed along an idea that should help get excellent results just entering straight keywords. We’ve got 91,000 documents indexed in there, and the searches are zippy even on a fairly modest box. Lucene is certainly very performant.
Kudos to Michael Franken for putting together Zilverline and making it available! (Soon to be open source, apparently. For now it’s just free.)