In order to save you time, I've compiled a list of PHP, Perl, and JavaScript regular expressions for common use cases that have been tested and are ready to go. This isn't a regular expression tutorial or even a reference; you can think of it more as a cheatsheet for when you just need the regex but don't want to put a lot of time into relearning regular expressions.
If you're looking for regex tutorials or regex resources, you can find them at the end of the page as well as some additional regex resources.