Finding out which country a user comes from using $_ENV[HTTP

meetn2veg has asked for the wisdom of the Perl Monks concerning the following question:

I know there's a way....

By using one of the UNIX $_ENV[HTTP_...] vars, you can find out (more or less) which country a visitor comes from.

Any ideas on which $_ENV var does this? I know it has something to do with resolving the IP address and also if the server as it activated, but....

Thanks again