teamwork - the open source team work management software: "Teamwork is a software application specifically for team work management. If your company works in teams then this is the application for you, as you can manage large volumes of information and operate effectively with your team members on complex projects. Teamwork will improve worklife quality, helping production cycle information flow management, via stage coordination and allocating tasks to everyone involved. As an application, Teamwork combines document management, groupware and project management features in a new perspective."
It really looks promising to me, especially when looking at the screenshots.