Check out this map that tracks Twitter activity in NYC. It was created by Eric Fischer, based on the Twitter streaming API.
"It is an attempt at plotting flow of people, in particular the paths from each place that someone posted a geotagged tweet to the next place that they posted one, and because I don't know anything about what they did in between, routed along the path in between that passes through the most other geotagged points," Fischer said.
He notes that Broadway serves as the "spine" of the traffic. More interesting though, in our opinion, is the traffic's resemblance to a gecko, if you picture Broadway as its backbone. What does this mean?