Top 2 alternative sites to pcre.org
RegExLib.com - The first Regular Expression Library on the Web!
Regular Expression Library provides a searchable database of regular expressions. Users can add, edit, rate, and test regular expressions.
RegexPlanet - Online Regular Expression (Regex) Testing and Cookbook for: Go, Haskell, Java, JavaScript, .Net, Perl, PHP, PostgreSQL, Python
RegexPlanet - Online Regular Expression (Regex) Testing and Cookbook for: Go, Haskell, Java, JavaScript, .Net, Perl, PHP, PostgreSQL, Python, Ruby, Tcl & XRegExp