Committers are contributors who have written lots of important code, sacrificing all social events, and becoming a hermit at the expense of providing good tools for people they don't even know. In return for their love and devotion you may bug them with questions, bug fixes, patches and offer them free beer.
Contributors are responsible for making this a better project and we all end up benefiting from the bug fixes, design changees or features they contributed. Contributors tend to live a balanced life and hopefully eat a healthy diet.
Documentors do the impossible and actually explain how to use the software in spite of all the complexity introduced by the committers and contributors.
The following have offered valuable feedback (including bug reports) that has been beneficial to the development and stability.