Frameworks

• CodeIgniter

CodeIgniter is a powerful PHP framework with a very small footprint, built for PHP coders who need a simple and elegant toolkit to create full-featured web applications. If you're a developer who lives in the real world of shared hosting accounts and clients with deadlines, and if you're tired of ponderously large and thoroughly undocumented frameworks, then CodeIgniter might be a good fit.
http://ellislab.com/codeigniter

• Yii

Yii is a high-performance PHP framework best for developing Web 2.0 applications.
http://www.yiiframework.com/

• Symfony

Symfony is a PHP framework for web projects.
Speed up the creation and maintenance of your PHP web applications. Replace the repetitive coding tasks by power, control and pleasure.
http://symfony.com/

• Doctrine

The Doctrine Project is the home of a selected set of PHP libraries primarily focused on providing persistence services and related functionality.
Its prize projects are a Object Relational Mapper and the Database Abstraction Layer it is built on top of
http://www.doctrine-project.org/

• Gearman

Gearman is an open source application framework
Gearman is designed to distribute appropriate computer tasks to multiple computers, so large tasks can be done more quickl
https://en.wikipedia.org/wiki/Gearman

Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work.
It allows you to do work in parallel, to load balance processing, and to call functions between languages
http://gearman.org/