SearchMyFiles - Alternative to the standard Search For Files And Folders module of Windows. Duplicates search is also supported.

Expressions - An app to play with regular expressions. Easily and nicely.

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, ...

RegEx Lab - RegEx Lab allows you to test regular expressions.

dnGREP - dnGrep allows you to search across files with easy-to-read results.

Multi String Replacer - Replace multiple strings at once!