USNG
The USNG Web Service returns the United States National Grid Coordinate for a specific latitutde/longitude point or the Latitude/longitude for a USNG position. View the detailed USNG Methods description for more information on the methods and parameters used in this service. Visit http://gisdata.usgs.net/ to view other USGS Web Services.The following operations are supported. For a formal definition, please review the Service Description.
Get_USNG Returns a United States National Grid Coordinate for a given latitude/longitude point specified in decimal degrees. Get_XY Returns a latitude/longitude point specified in decimal degrees for a given United States National Grid Coordinate.
More information: http://cumulus.cr.usgs.gov/XMLWebServices/USNG.asmx