Google Desktop Search on steroids. GDS has been updated and can now search virtually any part of your file system, thanks to specific plugins. Get the updated version from desktop.google.com. Great stuff. But to make it really useful, here are the power toys:

Index any text file - allows GDS to index any text file on your system, including log files, source code, or anything else.

Google Kongulo plugin - allows GDS to index web sites, such as your corperate intranet.

Geekzone - how to use GDS to index network drives

and the ultimate...

DNKA - remote desktop search tool - Access GDS remotely! Install at home, and search your home PC from work, and vice versa!

Hook that lot up and you will have extreme search at your fingertips.

UPDATE: Another add-on for firefox users: a Mycroft plugin (The search box in Firefox)