in reply to Learning regexes
regexEvaluater may be of interest if you would like to take a more interactive approach.
It has menu options to insert special characters, character classes, posix character classes, quantifiers and groups. There are menu options to add regex options e.g. add 'giosm' to the end of a function. You can load a text file and run the regex on it, and it will hilight the matches, there is also an option to save the transformed text. There's also an option to save the regex as a script.
You will need Perl 5.6 and Perl/Tk. It's a nice tool, check it out.