Debian GNU/Linux is a free distribution of the GNU/Linux operating system. It is maintained and updated through the work of many userswho volunteer their time and effort.
Super-fast and great-looking, Ubuntu is a secure, intuitive operating system that powers desktops, servers, netbooks and laptops. Ubuntu is, and always will be, absolutely free.
FreeBSD is an advanced operating system for modern server, desktop, and embedded computer platforms. FreeBSD's code base has undergone over thirty years of continuous development, improvement, and optimization.
CentOS -- Community ENTerprise Operating System is a free rebuild of source packages freely available from a Prominent North American Enterprise Linux vendor.
QPHP is an event-driven(EDP), component-based web framework similar as architecture to ASP.NET
An Object Oriented Framework for PHP, Zoop Framework caters to the programmer and includes ajax and validation. Zoop also features a PHP implementation of.
Extending the art & spirit of PHP, Zend Framework is based on simplicity, object-oriented best practices, corporate friendly licensing, and a rigorously tested agile codebase.
A bottom-up rewrite of the PHP scripting engine. It features a modular architecture, vastly improved performance, and greater scalability.
PRADO is a component-based and event-driven programming framework for developing Web applications in PHP 5. PRADO stands for PHP Rapid Application Development Object-oriented.