Ruby On Rails Content Management System: Radiant
With a very simple interface, Radiant offers flexibility when creating the design & content. 3 parts: pages, snippets (like PHP includes) and layouts create the core of the system.
It offers a flexible site structure where pages can be arranged according to any hierarcy.
Radiant has a custom template language named Radius (similar to HTML) which can be used inside pages, layouts to include content from other pages or display content conditionally & more. It also has an intelligent caching mechanism which helps serving pages faster while ensuring the content is up-to-date.