This SDK is NodeJS bindings for Or-tools Vehicle Routing Problems, Travelling Salesman Problem (TSP) and Vehicle Routing Problem (VRP) solvers. The Matrix API returns travel times between many points and allows you to build tools that efficiently check the reachability of coordinates from each other, filter points by travel time, or run algorithms for solving optimization problems. Mapbox is an open source mapping platform for developers.
There are any number of questions that can be answered by Wikipedia, but you can add "where am I?" to the list. Given any latitude/longitude coordinates, the WikiLocation API will find you corresponding Wikipedia articles to tell you about your surroundings.
Once upon a time there was the great debate over JSON vs XML. The past few years have seen JSONs popularity rise despite XML (and other formats) being well-established. Our own statistics on ProgrammableWeb show a significant increase in the number of JSON APIs over 2009/2010. During 2009 there were only 191 JSON APIs registered. So far in 2010 there are already 223.