I've seen this in the e-commerce module and wanted to know how to use it in the CMS for custom drop-downs:

if( ! $fields->fieldByName( 'Country' ) ) $fields->push(new DropdownField('Country', 'Country', Geoip::getCountryDropDown()));
}

This one clearly calls a function to get the GEO target, but how do I add a list of values here? Oh, and for this example as well, how do I add a default value if nothing is found?

Thanks for any hep in advance!