Great annotated list by Dennis Crowley of places that contributed to the creation of Foursquare.
Foursquare (and it's predecessor, dodgeball.com) were designed and built in downtown NYC. Here's a walking tour of where a lot of the ideas came from.
As Steven Johnson said, this is a "case study in how urban space fosters innovation".
If you're running the NYC marathon tomorrow, have an iPhone, and are a Foursquare user, 4SQ CEO Dennis Crowley has the low-down on how to track your progress throughout the race by auto-checking-in to 4SQ at all the mile markers.
I'm going to use Mayor Maker tomorrow during the NYC Marathon to auto check me in to every mile marker as I run past them. I'll be running w/ my iPhone in my pocket (with GPS turned on). Every time I run over a mile checkpoint, Mayor Maker will send that checkin to foursquare and foursquare will send it back out to Facebook and Twitter. Cool, right?
Foursquare co-founder Dennis Crowley recently gave a talk at a Brooklyn middle school; the Q&A included the following Qs:
Who's your favorite basketball player?
Have you every met anyone famous?
Can you really see Jupiter's moons with binoculars?
Do you know the guy who made the Sidekick?
Have you met any hip hop stars?