Is Concrete5 The Right CMS For Your Website?
10 Promising Content Management Systems
ResourceSpace: Open Source Digital Asset Management (DAM)
ResourceSpace is a web-based, open source digital asset management system which has been designed to give your content creators easy and fast access to print and web ready assets.
Open Atrium
Intranet, open source, built on Drupal with some nifty features. Looks nice too.