<?php
include("geoip.inc"); //library
$gi = geoip_open("GeoIP.dat", GEOIP_STANDARD); //open database

//fetch image
<img src="images/country_flags/_' . strtolower(geoip_country_code_by_addr($gi, $ip)) . '.png" title="Server located in ' . geoip_country_name_by_addr($gi, $ip) . '" />
?>