Drupal Commons
Drupal Commons is a Drupal distribution billed as “social business software.” That means that Acquia is distributing Drupal bundled with some other modules preconfigured to work as a company’s interactive user-facing website.
The result is a solid starting point for large businesses to make the transition to building relationships with their customers over the internet. Drupal Commons provides a fairly complete business-oriented community structure out of the box.
Drupal Commons revolves around Organic Groups. A Commons-based website essentially consists of a bunch of groups, each of which can have their own forums, wikis, blogs, documents, polls, and activity stream. There are also userpoints, email notifications, bookmarks, user relationships, and a WYSIWYG editor (CKEditor, to be precise). Users and groups have pretty comprehensive dashboards that can be customized by administrators.
-- From Mediacurrent review
Setup
Drupal Commons is set up as a standard Drupal 6.