pgeodns is a simple DNS server that can distribute load for a 
hostname to the nearest mirrors (as defined by geography; on the 
country / continent level).

It is used for search.cpan.org/cpansearch.perl.org and for 
ftp.perl.org/ftp.cpan.org; to provide nearby-ish 
servers for the NTP Pool; and to balance svn.apache.org to
svn.us.apache.org and svn.eu.apache.org.

WWW: http://geo.bitnames.com/