Check out this article over at SciAM:
It seems there’s an online community or social network for every facet of life these days. One area where this makes a lot of sense is in map-making, given how well locals know their own territory. This might explain why OpenStreetMap—a map of the world that can be edited by anyone with Web access—has expanded from 100,000 contributors in June to more than 180,000 (and claims to be adding 300 new mappers daily).
