DocFetcher - DocFetcher is a portable German/English open source desktop search application.
regexxer - regexxer is a nifty GUI search/replace tool featuring Perl-style regular expressions.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
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, ...
SMF – Search my Files - SMF - Search my Files v13 is the fastest duplicate files finder and a multi-dimensional - file searcher, - file copier / mover, - file deleter / eraser, - and
dnGREP - dnGrep allows you to search across files with easy-to-read results.