Tilemath
Math for map tiles, taken from http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/
Install
npm install
Test
grunt vows
Usage
var tilemath = require( 'tilemath' );
var bounds = tilemath( 5, 5, 12 );
// [40.979898069620155,123.75,31.952162238024975,112.5]