Open Source

Achievo
A web-based project management tool, offering basic project and customer management. (PHP)
http://www.achievo.org

Air Todo
Offers a project management tool with zero administration.
http://airtodo.sourceforge.net

Austin
C++ parser for which converts XML-based project files into Gantt charts.
http://austin.sourceforge.net

dotproject
BSD-licensed PHP-MySQL web-based project management application, with Gantt chart support.
http://www.dotproject.net/

Double Choco Latte
Issue tracking and project management. Part of Gnu Enterprise project.
http://dcl.sourceforge.net/

Eberom
CRM and Project Management Tool developed with Java and running with MySQL and TomCat. [GPL]
http://sourceforge.net/projects/eberom/

FUTURe Project Planner
A time management application written in Java including todo lists, Gantt charts, diaries, pert charts. Currently in early project stages.
http://www.wolfkeeper.uklinux.net/FUTURe/

Gantt Project
Graphical Java program for editing Gantt charts. GPL
http://ganttproject.biz

Gforge Project Management Tool
This part of the GForge collaborative development environment allows fine-grained control over tasklists, bugtracking, and gantt charts, with account management integrated into the overall product.
http://gforge.org/

jToDoList
Provides a todolist application written in Java.
http://developer.gauner.org/jtodolist/

PHProjekt
Web-based groupware tool which includes calendar, project-management, time-card management, PDA synchronization, email, voting system and personal to-do list management.
http://www.phprojekt.com

Project Management Interface
Web-based project management application. Provides portal management to a large number of coarsely-managed projects.
http://majordojo.com/pmi/

Project Open
Web-based project resource planning system, with project rooms, and tools for managing clients, invoices, time, and cost. Designed for the advertising, IT consulting, translation and knowledge management sectors.
http://www.project-open.com/

Projectory
Open source, platform-independent, web-enabled project management tool for software projects based on Perl and MySQL.
http://projectory.sourceforge.net/

PyGantt
Reads a project description from a XML formatted file and outputs an HTML Gantt diagram.
http://www.logilab.org/pygantt/

ScrumWiki
Simple Wiki-based tool for applying Scrum project management techniques. Collaborative, open source, cross platform and with full version control.
http://scrum.minty.org

Taskjuggler
A tool to schedule and track complex projects. The textual project description is compiled into schedules, status reports and GANTT charts.
http://www.taskjuggler.org

ToutDoux
A project manager for GNOME part of the GNU project. French/English.
http://www.gnu.org/software/toutdoux/

Track+
Issue tracking system. Web based tool for bug, issue, and task tracking. Offers Gantt charts, diagrams, configurable workflows, email reminders of due tasks and PDF reports.
http://www.trackplus.com/

TUTOS Groupware Suite
Web-based groupware suite.
http://www.tutos.org

WebCollab
A web-based system for projects and project management.
http://webcollab.sourceforge.net/

WR Time Tracker
PHP-based work time tracking system, under X11-style "Liberal Freeware License".
http://products.wrconsulting.com/wrtimetracker