Currently using CakePHP. Pretty small and clean. Easy to use.
1. Zend Framework - http://framework.zend.com/
2. CakePHP - http://www.cakephp.org/
3. Symfony Project - http://www.symfony-project.com/
4. Seagull Framework - http://seagull.phpkitchen.com/
5. WACT - http://www.phpwact.org/
6. Prado - http://www.xisc.com/
7. PHP on TRAX - http://phpontrax.com/
8. ZooP Framework - http://zoopframework.com/
9. eZ Components - http://ez.no/products/ez_components
10. CodeIgniter - http://www.codeigniter.com/
That's the top ten framework. For more information on other framework. below is the link
http://www.phpwact.org/php/mvc_frameworks
Cheers.
