New York City's system of buses and trains--the Metro Transit Authority--provides its data for download and inclusion in developer applications. All routes and schedules are available by borough in Google's GTFS format. Additionally, service status (ie, delays) and elevator/escalator status messages are updated every five minutes and available via XML feed. Finally, turnstile traffic is available at per-unit levels in four hour increments, with data refreshed weekly.
The MTA continues to make data available, including bridge/tunnel traffic and GIS files of subway entrance and exit points. Coverage includes all of the MTA's services, including the bus, subway, Long Island Rail Road, Metro North Bus, Long Island Bus and Bus Company.