mlocate - Indexes filesystems allowing you to search for files.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
fd - A simple, fast and user-friendly alternative to 'find'.
Drill - Search files without indexing, but clever crawling
NTFS-Search - This tool enables users to search their NTFS formatted harddrives within seconds.
Rapidshare Search Shared Files - Rapidshare Search Shared Files