Lite is the description OpenSourceCMS.com uses to refer to a Portal/CMS that does not require a database to function. These systems are very easy to install, but generally lack the sophistication of a database driven content management system.
GetSimple is an XML based lite Content Management System. To go along with it's best-in-class user interface, we have loaded it with features that every website needs, but with nothing it doesn't.
gpEasy is a complete content management system that lets users create rich and flexible Web sites with a simple and easy-to-use interface. The embedded design of the admin interface allows users to instantly see changes in a single browser window.
Pluck is a CMS written in PHP, that aims to be as simple as possible. With pluck you can easily manage your own website without knowledge of programming languages. This makes pluck an excellent choice for every small website.
OneFileCMS is just that. It's a flat, light, one file CMS (Content Management System) entirely contained in an easy-to-implement, highly customizable, database-less PHP script.
FlatNuke3 is a CMS (Content Management System) that makes no use of DBMS, but only text files (so its name).
Template CMS — fast and lightweight content management system, which allows you to easily create a promo site, satellite, personal page of a person who has no experience in PHP or HTML.
Easy, customizable, flat-file, content management system (CMS). It uses only text files and will run on any server where basic PHP5 fread()/fwrite() exist. Includes module system, easy templating (any layout can be integrated), WYSIWYG editor and more!
Stash — content management system (CMS). Was written on PHP and uses MySQL. Distributed under The Creative Commons License.