Joining OSS discussions made me mind my etiquette and educate myself to ask better questions [1]. This, conveniently, benefits my (writing) communication at work.

My favourite quote:

"You will earn an answer, if you earn it, by asking a substantial, interesting, and thought-provoking question — one that implicitly contributes to the experience of the community rather than merely passively demanding knowledge from others."

[1]: http://www.catb.org/~esr/faqs/smart-questions.html