The ArsDigita Community System (see also ACS) is an AOLserver toolkit from ArsDigita to help make your web site rule the savage wasteland.
The toolkit offers most of the features and capabilities important to any large and dynamic website, including catalog for e-commerce, a shared searchable file system, web-based content management, and a spectrum of community applications.
Unfortunately, ACS is built to be used with Oracle, but there is a project OpenACS that uses PostgreSQL for a totally open source solution.