Mink is an open source acceptance test framework for web applications, written in PHP 5.3. Check out more in here http://mink.behat.org/
Read: Mink - open source web application testing framework
WordPress is an open source Content Management System (CMS), often used as a blog publishing application, powered by PHP and MySQL.
Read: WordPress
Recently at Cambridge Software, we have been investigating different JavaScript based microframeworks for building rich applications that bring a desktop experience to the Web. Backbone.js is an excellent library, very lightweight, giving you a great deal of flexibility while covering all the foundation-type work. Backbone.js is built around the MVC pattern, it gives you base classes for models, controllers and views.
Read: Backbone.js + PHP (with Silex microframework) + MySQL