Dreamsteep

NetOffice is a free web based project-management environment written in PHP and MySQL. NetOffice allows managing and sharing information about teams, projects, tasks, deadlines and much more. Its intuitive interface makes it a fast and optimal solution for small to medium sized companies or organizations.

Though NetOffice has not been updated for a while, it is worth consideration. I have made it available here because it is getting hard to locate a download source for it online.