Open Source Web CMS Distros
The Drupal Distro for Publishers
OpenPublish is a packaged distribution of Drupal, tailored to the needs of online publishers. First released about a year ago, it has quickly gained momentum. It already has hundreds of active installations, thousands of downloads, professional support from me and my crew as well as other Drupal shops. It is the obvious choice for news publishers who want to get a head-start on Drupal.
Open Atrium - The open source web cms distro for Intranets, Teams, Groups.
Open Atrium is a team portal starter package. What makes it unique is that it's extensible and customizable. This means that you - and everyone - can develop new features for it, add other modules, change the skin, totally re-factor the workflow, and do anything else that you can think up to make Open Atrium meet your exact needs. Check out the Developer FAQ to get started. OA uses open source web cms - Drupal - as the base platform. This means that many of the Drupal contributed modules will work with OA.
We open sourced Open Atrium because we see it as a seed for something much larger - a community that makes great team communications tools. And it's working. Open Atrium is being translated in more than twenty languages and several hundred people are growing its base of features. Together we can develop the most advanced knowledge management tools.
Drupal Commons is a ready-to-use solution for building either internal or external communities. It provides a complete social business software solution for organizations.
Drupal Commons helps organize content into topic (organic) groups with blog, discussion, document, wiki, and event content types. It also allows users to create (user) relationships with each other in order to follow each other's activities on a site. Authenticated users can view a personalized dashboard containing content from all their subscribed groups.
Pressflow is a distribution of Drupal with integrated performance, scalability, availability, and testing enhancements.
Each version of Pressflow is API-compatible with the same major Drupal version. For example, Pressflow 6 is compatible with all Drupal 6 modules. Pressflow 6 also integrates the SimpleTest system from Drupal 7 and the CDN support patch. See the wiki (linked below) for more documentation.
An alternative to using these distro's is to take advantange of features that can easily be plugged into Drupal. The features.module is proving to be incredibly powerful for extending Drupal. Say for example, you want to set up a site to make and keep track of meetings.