A object-oriented and modular designed framework for developing web applications. psx separate strictly code from design with a template-engine based on XML and XSLT.
A web application framework for PHP Developers that includes a framework for code modules and layout templates, database connectivity, SmartForms, sessions, and other tools. [Open source, Q Public License]
A set of PHP classes and library functions to help facilitate building, debugging, and rendering of XML, HTML, XHTML, WAP/WML Documents, and SVG (Scalable Vector Graphics) images as well as complex HTML 'widgets'. [Open source, LGPL]
An Object Oriented Framework for PHP, Zoop Framework caters to the programmer and includes ajax and validation. Zoop also features a PHP implementation of .NET controls called GUIControls [Zope Public License, GPL compatible].