"OpenProj is a free, open source desktop alternative to Microsoft Project. The OpenProj solution is ideal for desktop project management and is available on Linux, Unix, Mac or Windows. OpenProj is a complete desktop replacement of Microsoft Project and even opens existing native Project files. OpenProj shares the most advanced scheduling engine in the industry with Projects On Demand. The OpenProj solution has Gantt Charts, Network Diagrams (PERT Charts), WBS and RBS charts, Earned Value costing and more. You can get more detailed information on OpenProj or download now! "
"Collabtive is web-based project management software.
The project was started in November 2007. It is Open Source software and provides an alternative to proprietary tools like Basecamp. Collabtive is written in PHP and JavaScript."