Lithium, the most RAD framework for PHP 5.3+ is focused on quality, speed, and flexibility. It's a set of no-nonsense philosophies and tools that enable you to build better applications, in less time, without sacrificing quality or extensibility.

Lithium understands distributed storage and caching, queuing systems, micro-dispatch frameworks, with integrated support for document oriented databases like CouchDB and MongoDB, alongside relational databases like MySQL and PostgreSQL.

Lithium's architecture allows you to get your application up and running quickly, and still allows you to take control of the framework to support the requirements of your application.

Source: Lithium