RegExRX for Mac

From MacTechnologies Consulting:

RegExRX is a regular expression editor and tester with many features designed to help in the development and storage of regular expressions. Based on the PCRE library, RegExRX will allow a user to craft patterns that are compatible with most regular expression flavors and will let them easily copy those patterns to other languages like Perl, Ruby, PHP and REALbasic.
RegExRX is a complete tool meant for novices and experts alike. Some of its features include:

• Search and Replace modes.
• Color-coded tokens in both the "search" and "replace" patterns.
• Live matching against source text. Live replace too, where applicable.
• Insert menus with almost every acceptable token and a description of what they do, including constructs for various groupings, conditionals, lookarounds, and POSIX expressions.
• A "Match List" that shows all matches, with subexpressions, and represents invisible characters like a space or return with their token equivalents ("\s" or "\r").
• Stats on both the source text and replaced text so you can tell exactly where you are and what characters are represented at all times. Helps avoid errors caused by invisible characters.
• Linked scrolling among the source text, the replaced text and the Match List.
• Save regular expressions in documents for reuse.
• Open as many windows as desired.
• Multiple levels of undo.
• Link your sample source text to a file for easy reloading.
• Support for free-spacing mode.
• Full Unicode support, including a chart of all UTF-8 characters.
• A fluid interface that lets you resize each panel freely.
• Copy the find and replace patterns in ready-to-paste code for Perl, PHP, Ruby, AppleScript and REALbasic.

MacTechnologies Consulting also provides several ready-to-use sample regular expressions in a separate, free download. These samples include finding e-mail addresses, validating dates, removing duplicate lines, and more.