The OpenStreetMap-api-client PHP SDK by Mauro Moreno is a PHP client for the OpenStreetMap API. The OpenStreetMap API has various aspects. Part of it's services provides read and write operations on the raw map data of the OpenStreetMap database.
Forecast, the team that created the acclaimed iOS weather app Dark Sky, has created an API that brings its gorgeous weather data and display into any platform. As Forecast put it, they wanted to transcend their work with Dark Sky.