From a software developer's point of view, maintaining a gantt chart (such as marking off tasks as complete or reassigning them, etc) can become cumbersome when dealing with a separate piece of software to that of the development process.
Currently, I utilise Trac to create/manage tasks for the project, and have an SVN hook which marks them complete as I commit new code. What Gantt chart software can provide this kind of tightly coupled integration for myself and a small team (2 - 3)?