The WRLD Windows SDK allows developers to run the WRLD API through this C# SDK on Windows devices and applications. The main SDK method is embedding a 3D map. WRLD is a company that creates and provides interactive 3D maps for a variety of operating systems/devices, such as iOS, Android, OSX, OculusVR, and WebGL.
We have covered BigML.com API for making machine learning models here before. Recently BigML made some innovative changes including new data visualization and new classification ensemble models, all doable by API. Here is an interview with Fransisco J Martin, CEO of BigML.com.
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.
It's no secret how big map mashups are on ProgrammableWeb. That means we've seen many and the really great ones stick out. In fact, two of these three mashups don't even use a map. But they all use location-sharing service Foursquare.