TL;DR Version: I wrote a tool called GIPC (short for Geographical IP Correlation and pronounced Gypsy) which takes a list of IP address and returns the Geographical information you select based on the MaxMind.com GeoCity Database.
The exe requires 2 inputs: The IP file (one IP per line) MaxMind GeoCity database – This can be downloaded HERE:http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz
Please read more on my blog: http://jcsocal.blogspot.com/2013/03/geographical-ip-correlation-tool.html
PortscanGeoinfo is a plugin for the powerful Prelude correlation engine. This plugin correlates alerts from Snort NIDS and OSSEC HIDS sensors regarding portscans. Geographical information (GeoIP) is included in the correlated alert.
MaxMind GeoIP is a set of APIs for looking up the location of an IP address, including the country, region, city, latitude, and longitude. Free GeoLite databases are available at http://www.maxmind.com/app/geolitecity