Baagle Desktop Search
Baagle Desktop Search is a work-alike to the Google Desktop Search. It is primarily designed for UNIX-like systems, but works passably on Windows (it's received about 10 minutes of testing using ActivePerl and Swish-E for Windows; YMWV) The basic principle is that you run an indexer that indexes all of your files, then run a simple dummy webserver which serves you the results of searches in a convenient web environment.
Here are some screenshots of Baagle Desktop Search in action:
Download: baagle-2.0.tar.gz (24K)