OpenStreetBlock is a web service for turning a given lat/lon coordinate (e.g. 40.737813,-73.997887) into a textual description of the actual city block to which the coordinate points (e.g. “West 14th Street bet. 6th Ave. & 7th Ave”) using OpenStreetMap data.
There are likely many applications for such a service. It should be quite useful any time you might need to succinctly describe a given location without using a map.