The Tripian City List Curl Sample Code demonstrates how to interact with the API to access over 200 cities world-wide. Each city has a unique id (city_id) to create trips, trip-related questions, and get quick recommendations.
As a DC-area resident, I've been one of many local developers saying that the DC Metro needs some sort of API. If anything, just to be able to build or integrate transit routes into existing apps. The wait appears over and the Washington Metropolitan Area Transit Authority now has an API.
Google has announced that on April 10, 2018, it will cease offering the QPX Express API that provides developers access to airline pricing and shopping through a standard API. Google acquired the technology behind the QPX Express API when it completed its acquisition of ITA Software in 2011.
A new bicycle wheel prototype is connecting the non-technical, everyday world to the Web. The Copenhagen Wheel attaches to an ordinary bike and helps its owner collect fitness and location data. From an iPhone, the rider can also see traffic and polution information and share their own data with friends. This real world mashup is one of many we're bound to start seeing released as we make our move toward living in the future.