http://geogames.net/labs/geohex
GeoHex is introduced in Nobember 2009. It covers land and sea area in Japan. However, this concept could be applicable for other region.
GeoHex devide whole target area (Japan region) into honeycomb geometry regions. In other words, GeoHex use regular hexagonal grid instead of usual square or rectangle grid.

This style of dividing has been very popular in the world of video games, but GeoHex is the first application to apply hexagon dividing to real geographic world. Precision or size of hexagon is 60 steps. Size of GeoHex code is minimum 4 digits with smallest precision. GeoHex uses oblique coordinate system instead of orthogonal coordinate system as shown in following figure. It is possible to calculate distance between centers of any hexagon.

GeoHex code is calculated form/to latitude/longitude directly..
Sample Code:
310fMwD