It's an old cliche, but the saying 'if you want to learn a subject, teach it' holds a certain amount of truth. The act of ordering your thoughts and understanding about a subject allows you to spot the holes in your understanding, whether that subject is how to use a text editor or how nuclear fission works.
I've noticed this in many people, myself included. The primary case I would cite is the helpers in the IRC room #rubyonrails on freenode.net. The majority of newcomers will come into the room, ask a question, and leave (or remain silent) as soon as they have an answer. I've seen some of these people still asking the same sort of questions months or years after first appearing. The other newcomers are people that will ask some questions but will also try to answer other peoples questions straight away. These people have a tendency to develop all aspects of their development skills much quicker, as they are constantly exposing themselves to new situations that they would otherwise have never encountered.
Writing blog posts, doing podcasts, writing newsletters, helping out in a support channel. They're all ways to help teach other people and by extension help you to develop your own understanding further.
What are your preferences for helping develop the skills of team-mates, colleagues and your wider development community?