dotProject, a open-source project management tool is surprisingly not company owned. The web-based tool is a volunteer supported project

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management application. Delicious users bookmarked dotProject 3,105 times. Features of dotProject include:
- User Management
- Email Based Trouble Ticket System
- Client/Company Management
- Project Listings
- Hierarchical Task List
- File Repository
- Contact List
- Calendar
- Discussion Forum
- Resource Based Permissions
Here is what one user of dotProject, The Linux Knowledge Base and Tutorial, posted on the dotProject website:
"With all of the features and content we have, running the Linux Tutorial is not an easy task. We are constantly improving and adding to our already extensive offering. When we first started, all of our TODOs were managed with lists in various text files or piles of notes. As the site grew, the number of things we needed to keep track of grew considerably and our so-called management system was obviously not up to the task. After we tried a couple of different project management tools, we finally decided upon dotProject and never looked back.
We have defined projects for the major functional and content areas within the Tutorial. These serve to help organize the tasks and sub-tasks. Since we constantly upgrading and improving these sites, the individual tasks come and go, but these projects never end. Currently we are managing over 50 projects, with 300 tasks. With the limited number of people working on this project, it is still a daunting task. However, without dotProject it would be near impossible."