With increasing use of Map service such as google, yahoo and MSN one often need to calculate distance between two location. This can be done many ways I suppose. However, to calculate the short distance we can perform calculation based on longitude and latitude values of those two location.

 However, it is simply a math formula you need to learn but you should now the coordinates of location as well. Here is one beautiful article and Javascript method do to that

http://www.movable-type.co.uk/scripts/latlong.html

This script explain all its working and from where it is drived. Such a nice place to learn something new :).