I had heard about open source software, but it didn’t occur to me other stuff could be open source as well. A friend of mine published what was my first acquaintance with an open source book. At http://www.projectmanagement-training.net/ you can learn a lot about project management, and if you’re a project manager yourself you may want to add to it. You can also opt for a training, as the domain name most blatantly suggests.
I must shamelessly admit I have merely scanned over it, and haven’t added anything, although I’ve been a trainer (e.g. MS Project), a project manager, and a writer for quite a while.