JQuery forms

http://www.jquery.wisdomplug.com/jquery-plugins/jquery-forms-plugins-jquery-plugins/a-guide-to-creating-forms-in-jquery/

Regular Expressions

http://www.regextester.com/pregsyntax.html

PHP Forums

http://www.phpbuilder.com

PHP Manual

http://www.php.net/manual/en/

MySQL Manual

http://dev.mysql.com/doc/refman/5.5/en/

Drupal General concepts

http://drupal.org/node/19828

http://drupal.org/getting-started

http://drupal.org/documentation/customization/tutorials/beginners-cookbook

Drupal online sites

http://buytaert.net/tag/drupal-sites