Silverstripe Content Management System
Also balancing flexibility and simplicity, Silverstripe alos offers a framework for developers. That is why we like it, no need to reinvent the wheel. With silverstripe there is no need for complex and costly bespoke systems. Your business requirements can be aligned with a range of add-on modules and extensible functionality. The Silverstripe CMS is an open source project, however it uses the BSD licence (Berkeley Software Distribution Licence), which is good for business as you are not required to put customised in the open source version.
The company itself, Silverstripe, is based in New Zealand and has a few partners in Australia and the United States of America. Silverstripe may not have a massive followiing such as wordpress, joomla or drupal however it seems very elegant and impressive. Synergy Systems is looking into becoming a partner of Silverstripe.
Here is a more extensive list of silverstripe in practice.