Recently I posted about an interview with Jimmy Wales and only a couple days after that I ran across What Motivates Wikipedians in the November issue of ACM Communications. The motivations varied, with the primary ones being fun and ideology (knowledge should be free). There didn't seem to be one hugely compelling reason, but according to their numbers the average contributor puts in 8 hours a week.
That had me thinking about two things. First, maybe I should be contributing, both to give back some value and to better understand the work that goes into it. Adding that to my list, now to find a topic about which I can say something meaningful. The other point was a reiteration of something I already know; that communities are incredibly powerful things.