Google API

<script src="http://www.google.com/jsapi" language="javascript"></script>
<script language="javascript">
if (google.loader.ClientLocation != null) {
document.write("Your Location Is: " + google.loader.ClientLocation.address.city + ", "
 + google.loader.ClientLocation.address.region);
} else {
document.write("Your Location Was Not Detected By Google Loader");
}
</script>

 Демо: