I spoke with Josh Peterson of the Robot Coop for a podcast recently. He and the Robots are the creators of a network of sites including 43things.com and 43people.com. Another site of theirs, 43places.com is one of the social apps that we’re going to be examining during Where 2.0. 43places.com is a site built by its users. As I learned during our talk, they began with 4000 places and, through user contributions, have climbed to 60,000 places. We also discussed how they came to add events to 43places and how they are built using webservices from Yahoo, Google, Flickr, and Upcoming. You can learn more from the podcast (mp3).