For example, this blog is a direct result of MST asking me for a feed URL, not because we had a conversation about it, but because I told him that I liked the ironman challenge, and I found his lightning talk entertaining. In response, he told me he expected a feed URL for my blog.
Oh sh*t. Now I need to actually do something. Granted, it was unlikely that mst would remember me, or even know my name if I didn't follow through, but I had a well known member of the community ask me to do something for the good of the community. Now I am writing this blog, once a week, because Matt asked me almost offhandedly for a feed URL. If he hadn't spent that 20 seconds to ask me, but instead just said thank you for the compliment, this blog wouldn't be here.
In my own personal experience, I asked via a mass email if folks in my department at the University of Minnesota would like to help prepare and submit a bit for YAPC.
I then asked a few people directly, and got several "yeah sure, I'd love to help". As a result, we had a nice team of people for our bid for YAPC.
In fact my own involvement with the Perl community with talks and Frozen Perl was because my coworker asked me to help organize the event and submit talks. Now two years later I have written four 20 minute talks, helped organize two Frozen Perl workshops (leading one of them), and put together a complete YAPC bid. All because two years ago at this time, a coworker asked me to share the knowledge I did have, even though I wasn't an expert on any Perl topic.
The moral of this story is: If you want a vibrant community you need to be like MST and ask individuals to be involved. Ask them to do what they are good at. If your group needs to have a moderator on the listserve, or someone to organize social events at an event like YAPC or OSCON, that is a good job for someone who cannot code on your project.
This gives the non-technical folks or people unfamilliar to your project a chance to really help. Sometimes these jobs are just as important as the jobs for the 'really smart' guys. Imagine if noone ever organized hackathons/class space for Patrick Michaud to work on/teach Parrot. The Parrot project would look very different if he had to do all that work.
My topic for next week: Getting involved in the Perl community - how to get involved yourself