Here is a list of all desktop FREE search tool I have found so far, I am personaly using Google, but regret that there is no Linux version of it...

Windows only

Plattform independant   

x-friend's   (0.2.1 beta) search functionality includes full text search (using apache Lucene) and meta data search. Search results will be displayed within seconds and can be categorized by file type, date, size etc.

Additionally, x-friend searches the internet, product catalogues, internet news (RSS-feeds), emails and other search services. I will do a Review soon under Suse 9.2

  • Indexing of (Searching in) files, prictures, RSS-news-feeds, mails, etc.
  • Support of: MS-Office-files, PDF, RTF, HTML, XML, TXT, CVS, etc.
  • Usage of meta-information for digital-photos (EXIF-header) and MP3s (ID-Tag), etc.
Lucidity (http://almaw.com/java/wiki/LuciditySearch) "Lucidity is an Intranet search application designed to make finding documents on big Samba shares on your office/home LAN easier. It will also happily index local files on your hard disk.  

The search system is powered by Lucene and runs as a background process. The user interface is browser-based and is provided by a J2EE web app written using Tapestry. You'll need a servlet container like Jetty to run it, plus the JDK obviously."

Another program based on apache Lucene: http://www.peerfear.org/rss/permalink/2004/10/28/LotsOfInterestInLuceneDesktop/

Not FREE