and works across functional groups as well (http://trac.edgewall.org/). It is mainly geared towards software development efforts, and integrates very well with major version control systems. It also has an integrated bug-tracking system, wiki, and a host of plugins that allow for task-dependencies, project planning, binning tasks into specific milestones, setting time limits on sub-tasks, and in general everything you possibly want to do in a software development environment. In addition, you can create your own plugins, Gantt charts etc if so inclined. You mainly plan and execute projects through "tickets", which could be a task, bug, enhancement, whatever. The meta-data for each ticket can be customized, though the out-of-the-box implementation is pretty useful. And its open-source.