Joomla-Based Project Management System: Projectfork
Joomla, the popular open source CMS, has many components that extend its functionality.
Projectfork is a free component that transforms Joomla into a full-featured project management application.
An unlimited number of projects can be defined with each having unlimited tasks and milestones.
There is an ACL-based permission system where each user is automatically notified about the updates related to them via e-mails.
Also, upcoming tasks can be viewed inside a calendar (the dashboard presents them as well).
Files can be attached to projects and there are per-project discussion boards where every member of the team can share their opinions.
And, a built-in time-tracking system can report you how much time is spent on each task/milestone/project.