Finding the home country of a client using only the IP address can be 
difficult. Looking up the domain name associated with that address can 
provide some help, but many IP address are not reverse mapped to any 
useful domain, and the most common domain (.com) offers no help when 
looking for country.

This module comes bundled with a database of countries where various IP 
addresses have been assigned. Although the country of assignment will 
probably be the country associated with a large ISP rather than the 
client herself, this is probably good enough for most log analysis 
applications, and under test has proved to be as accurate as 
reverse-DNS and WHOIS lookup.

WWW: http://search.cpan.org/~nwetters/IP-Country-2.20/