dnGREP - dnGrep allows you to search across files with easy-to-read results.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
AstroGrep - AstroGrep is A Microsoft Windows GUI File Searching (grep) utility.
DocFetcher - DocFetcher is a portable German/English open source desktop search application.
PowerGREP - Quickly search through large numbers of files on your PC or network using powerful text patterns to find exactly the information you want. Search and replace with plain text or regular expressions to maintain web sites, source code, reports, ...
X1 Search - X1's Lightning-Fast Search Software. Premium Alternative to Windows Desktop and Outlook Search.