Oyster

Oyster helps you interactively build and test regular expressions--which aren't the easiest things to build and debug--storing each "pearl" in an easy-to-access library.
With powerful syntax highlighting, dynamic updates of matches, and the results of replacement patterns in test text, it has never been easier to build and test your regular expressions. Once you've got it just the way you like it, Oyster lets you copy the code in one of 11 languages onto the clipboard or by dragging out the pip into your desired editor. Starting with Dash 1.8.5 (coming August 2013) you can even save your regular expression as a snippet in Dash's library. You're not alone either: Oyster has built-in integration with Oyster Farm, an online repository for pearls.