Change store by location - Magento

gistfile1.php

$ip = $_SERVER["REMOTE_ADDR"];//cant use helper, not loaded yet

$location = file_get_contents('http://api.ipinfodb.com/v3/ip-city/?key=<api_key>&format=json&ip='.$ip.'');
$location = json_decode($location);

$country = $location->countryCode;

if(strcmp($country,'CA') == 0) {
    $mageRunType = 'store';
    $mageRunCode = 'en_ca';
}
else
{
    $mageRunType = 'store';
    $mageRunCode = 'default';
}

Mage::reset();

Add this to index.php just before Mage::run($mageRunCode, $mageRunType);

Why not to use maxmind geoip.dat + geoip.inc? At least there is no overhead of third party request.

Agree MagePsycho, this can be combined with geoip but Magento is not loaded at this point, so it should be a plain PHP script.