http://pivotx.net/

http://jaf-cms.sourceforge.net/

http://get-simple.info/

The Simplest Content Management System. Ever. GetSimple has everything you need, and nothing you don't

http://www.flatnux.altervista.org/

Flatnux is a CMS (Content Management System) with textual database easily customizable.

http://feindura.org/

feindura is a flat file based Content Management System written in PHP, which doesn't need a database. Just create your layout, integrate feindura in your website, upload it to your server and you're done.