GanttProject is a project scheduling application written in Java and featuring gantt chart, resource management, calendaring, import/export (MS Project, HTML, PDF, spreadsheets).

Ganttproject Features
MsProject compatibility (use mpxj | )
Move code as Eclipse plug-in.
Update task tree as a table.
Include vacations for resources.
Add undo/redo feature, Add the critical path of the project.
Improve parameters for the chart rendering.
Relationship + n-day configurable for each relation
Improve print, Could specify custom columns for the tasks
Save temporary state of the project, Could hide (and unhide) some tasks for the rendering.
Translations in Korean and Bulgarian.