I do a lot of work that involves brewing up regular expressions and then pulling bits out of them.
On Windows and Linux, I use [link|http://laurent.riesterer.free.fr/regexp/|Visual Regexp], which gets the job done, but the version I've got for OS X looks and acts like arse, and has some decidedly eccentric ideas about putting things on the clipboard.
So I googled around a bit and, oh lordy.
Hello, baby.
Let's dance.
[image|http://guildenstern.dyndns.org/tmp/kiki.png||||]
[link|http://project5.freezope.org/kiki/index.html/|Kiki] is a Python script that uses wxPython.
Suits you, sir! Ooh!