Perhaps best described as Etsy meets Model UN, DIYcity aims to empower citizens to collaboratively create "a city that is like the Internet in its openness, participation, distributed nature and rapid, organic evolution -- a city that is not centrally operated, but that is created, operated and improved upon by all." The brainchild of John Geraci, co-founder of local media aggregator Outside.in, DIYcity has spread from its roots in New York City to branches in more than 40 global cities, from Kuala Lumpur to Curitiba, Brazil. Two flagship projects are just getting off the ground. SickCity -- "realtime disease detection for your city" -- is an attempt to track the spread of diseases throughout urban environments through Twitter keyword searches. And DIYtraffic ties Yahoo traffic updates to a simple cell-phone SMS platform (powered, it seems, by Twitter). Solutions built out for one city are cycled back into the mix, so that developers across the world can pull from the best practices of their counterparts wherever they might happen to be. (Apologies for the fact that you will no doubt now have Jefferson Starship playing in your head for the rest of the day.)