I have been using a small PHP MVC Framework called Dingo Framework.
Dingo is a Rapid Development Application Framework written in PHP by Evan Byrme. Dingo allows you to create dynamically changing websites easily and quickly.
Dingo is a relatively new full-featured framework at a compact size of 70KB, It supports Fancy URL’s, Access Control List, User Authentication, ORM, and simple no SQL database interaction.
Dingo is very easy to leverage, adding 3rd parties libraries is dead easy. The configuration is simple with support for multiple database connections, autoload libraries and helpers.
Dingo is well documented, but a little outdated, You are probably better off checking GitHub for more up to date code.