Google has just announced the addition of a valuable new feature for the Google Maps API (the most popular API in our API directory): reverse geocoding. If you are not familiar with geocoding, it is the process of converting an address into a latitude/longitude pair. Likewise, reverse geocoding is the process of converting a latitude/longitude pair into an address. Developers using the Google Maps API have had access to geocoding since its release in June 2006, and geocoding has been integrated with many of the map mashups developed with this API.
Microsoft has launched the Bing Maps Distance Matrix API which returns the travel times and distances between a set of origins and destinations. The API can be used in applications to solve the Traveling Salesman Problem and Vehicle Routing Problem returning the best route for a set of locations.