Cross browser CSS gradient - http://webdesignerwall.com/tutorials/cross-browser-css-gradient
Doctype declarations - http://www.w3.org/QA/2002/04/valid-dtd-list.html
Open Sans Font - http://www.google.com/webfonts#UsePlace:use/Collection:Open+Sans
Oswald Font - http://www.google.com/webfonts#UsePlace:use/Collection:Oswald
PHP freaks - http://www.phpfreaks.com/
MSDN (Microsoft Dev Network) - http://msdn.microsoft.com/en-UK
Convert page to .jpg - http://www.sciweavers.org/free-online-web-to-image
eBay - http://www.ebay.co.uk/
Google - http://www.google.co.uk/
Google Maps - http://maps.google.co.uk/maps?hl=en&tab=wl
Make gifs - http://gifmake.com/
Wikipedia - http://en.wikipedia.org/wiki/Main_Page
YouTube - http://www.youtube.com/?gl=GB&hl=en-GB
Ajax - http://api.jquery.com/jQuery.ajax/
Ajax loader images - http://ajaxload.info/
Browser Shots - http://browsershots.org/
Javascript - https://developer.mozilla.org/en/docs/JavaScript
Jquery - <script src=\"//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js\"></script>
Jquery Site - http://jquery.com/
Jquery UI - <script src=\"//ajax.googleapis.com/ajax/libs/jqueryui/1.9.2/jquery-ui.min.js\"></script>
MySQL - http://www.mysql.com/
PHP - http://php.net/
PHP mailer - http://phpmailer.worxware.com/
Stack Overflow - http://stackoverflow.com/
Test sites on smaller devices - http://ipadpeek.com/
w3schools - http://www.w3schools.com/
World Wide Web consortium - http://www.w3.org/