I'm no longer maintaining this project & have taken it offline, but I'd love to hand the reigns to somebody who can push it forward.
For my first foray into data visualization and 'civic hacking', I built a webapp that plots entry & exit traffic at subway stations throughout New York City using the MTA's turnstile data.
I imported the raw MTA data into a MySQL database, stripped out unnecessary & erroneous data, and built a robust query & charting protocol to plot the charts online. It was quite a fun and educational experience!
Please note: because the scripts strip non-'REGULAR' & off-hour audit events from the MTA data, you'll occasionally find some missing data points on the chart. I'm working on a solution.