One of the primary difficulties a web site faces is managing content. This can include enabling multiple user levels access for content development and editing, establishing staging and production areas of a site, all while maintaining integrity of the design and application levels.
There is substantial open source development in content management systems (CMS) and there is of course a portal and organization devoted to aggregating access to the best open source systems available.
OSCOM – The international association for Open Source Content Management, brings together developers and users to improve and promote open source CMS. Be sure to see their extensive matrix of systems available.
OSCOM web site