regexxer - regexxer is a nifty GUI search/replace tool featuring Perl-style regular expressions.
dnGREP - dnGrep allows you to search across files with easy-to-read results.
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, ...
TextCrawler - Find and replace across multiple files
FileSeek - FileSeek is an easy-to-use file search app that includes advanced functionality for power users!
Search & Replace Master - Search & replace the text in your files in seconds.