This regular expression removes multi-line (star) comments from JavaScript, while leaving any CDATA sections intact. Use the global (g) modifier to match them all (if you plan to use PHP's preg_replace, the g modifier is not necessary), and use the (s) modifier to make dots match newlines (this will...

See http://tools.ietf.org/html/rfc2045#section-5.1

See http://www.php.net/manual/en/reflectionparameter.tostring.php

Valid PHP variable name as defined in the manual at http://php.net/manual/en/language.variables.basics.php

Matches distorted email addresses and converts them back to real ones.

A quite neat regular expression for URLs, e-mails..., I found on Matthew O'Riordan's blog.