If like me, regular expressions are constantly nagging at you because you just can't get the knack of them, you'll be happy to learn that I have finally found that software I have been waiting for all these years:
RegexBuddy. Behind this mindbogglingly dull name hides a very nice visual regular expression editor, debugger, tester and optimizer. Regular expression nirvana!
I am a completely lost case regarding regexes, so I have purchased a copy - and I can honestly say that's the most well spent money I ever spent on software (with the exception of Photoshop, I think). The integrated regexp parser tree view shows you exactly what a regexp is made of, what it matches, where you could optimize it as well as correct common errors. It supports Perl-Compatible regexes as well as POSIX extended ones, has integrated PHP syntax highlighting... I'll stop here before anyone thinks I am affiliated with the creators of the software (but you were probably already thinking just that).
As pictures tell more than words, I'll let these screenshots speak for themselves:
The regex wizards out there will probably laugh at this, but I can highly recommend it if you want to learn regular expressions or simply to be able to make some of your own without external help