The Bay Area d3 User Group, founded six months ago, is nearing 500 members and it's 10th event.
The group hosts workshops, hackathons, and open discussions of working with data and the d3.js library. It's run by Ian Johnson and Kai Chang, and made possible by Mike Bostock, Christophe Viau, Dow Street, Rich Morin, and Vincenzo Menanno