Pivotal Tracker is a free, award winning story-based project planning tool that allows teams to collaborate in real-time.

Tracker is a free, award winning story-based project planning tool that allows teams to collaborate in real-time.

Velocity tracking and emergent iterations
Make planning decisions using accurate projections based on past performance.
Story-based iterative planning
Base your software project management on proven agile methods.
Real-time collaboration
See what your team is doing and react to change instantly.
(Link: Pivotal Tracker is a free, award winning story-based project planning tool that allows teams to collaborate in real-time.)