PHP regular expressions examples

http://www.roscripts.com/PHP_regular_expressions_examples-136.html

http://www.catswhocode.com/blog/15-php-regular-expressions-for-web-developers

special characters

http://www.devguru.com/technologies/ecmascript/quickref/regexp.html

http://www.devguru.com/technologies/ecmascript/quickref/regexp_special_characters.html

http://www.regular-expressions.info/

http://www.zytrax.com/tech/web/regex.htm