Not exactly to your requirements but related: we use the MaxMind GeoLite city database to correlate IPs with lat/lon and city/country names.  It's free (the GeoLite version; the pay version has a little more detail but doesn't cost very much) and simple to update and use.<p><a href="http://www.maxmind.com/app/geolitecity" rel="nofollow">http://www.maxmind.com/app/geolitecity</a>