HTML5 Geolocation

http://diveintohtml5.info/geolocation.html

http://msdn.microsoft.com/en-us/library/windows/apps/hh441080.aspx

https://developer.mozilla.org/en-US/docs/WebAPI/Using_geolocation?redirectlocale=en-US&redirectslug=Using_geolocation

http://msdn.microsoft.com/en-us/library/ie/hh772291%28v=vs.85%29.aspx