The Google Geocoder API transforms addresses into geographical locations with coordinates. This official Java library has the potential to expand functionality due to the other APIs that include directions API, distance matrix API, elevation API, geocoding API, roads API, and time zone API. Working with this library could facilitate automatic rate limiting, retry on failure, easy authentication, and asynchronous & synchronous requests.
Earlier this month I eulogized the Yahoo Maps API. It was launched the same week as the Google Maps API and for some time was often mentioned at the same time. The Yahoo Maps API, it appeared, was to be disconnected by now, but it appears the company is going to wait a bit longer.
Zillow has released an application for iPhone users that builds on their Zillow API, the Microsoft Virtual Earth API and the iPhone's GPS capabilities. The Zillow iPhone app detects your location and shows data about nearby homes, including market values, photos, and which ones are for sale. It's a great example of a mobile mashup application that uses multiple APIs in meaningful location-aware context.
Years ago most schoolchildren in the US "knew" that if you dig a hole straight down through the earth you end-up in China. But of course that's not true, no matter where you are in the US. From nearly anywhere in the contiguous 48 states you end-up in the Indian Ocean.