GanttProject is a free and easy to use Gantt chart based project scheduling and management tool.
It comes with:

* Task hierarchy and dependencies, milestones, baselines.
* Gantt chart with an option to generate PERT chart.
* Resource load chart.
* Task cost calculation.
* Export to PDF, HTML, PNG.
* Interoperability with MS Project, Excel and other spreadsheet apps.
* Basic WebDAV based collaboration.

Besides, a commercial collaboration service GanttProject Cloud is integrated into GanttProject.

Visit http://ganttproject.biz to learn more.