GanttProject is a project scheduling application written in Java and featuring Gantt chart, resource management, calendaring, import/export (MS Project, HTML, PDF, spreadsheets). Learn more on http://ganttproject.biz
TimeFinder automatically optimizes schedules (timetables) for universities and high schools. It makes manual timetabling for the timetabler easier via a Java GUI. Export+import is supported via xml and text formats. http://timefinder.sourceforge.net/
Timmon is a time tracking tool helping to keep track of time spent on different projects. Timmon lets you organize your tasks hierarchically, supports day, week, month and year views. Data is stored in XML. Provides monthly reports (pdf,html,xls,csv,...)