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. It is also used to provide nearby-ish servers for the NTP Pool.
It's not quite as feature rich as we would like, but it gets the job done. (And it's not much code so you can probably add in whatever you need). :-) For feature requests, see the link to the issue tracker below.
For our use we need less than 200 DNS lookups per second per DNS server, so we don't know how well it scales. (But on modern hardware the answer is likely "well enough for what you need"). The plan is to make pgeodns work as a PowerDNS plugin to make it (much) faster and easier to scale across multiple CPUs, but we haven't needed it enough to get around to implementing it yet.
The latest release can be downloaded from the downloads page. The git repository is at at git.develooper.com and github.
We have an issue tracker and a mailing list. We also have an ohloh page. :-)
Email ask@develooper.com with questions, comments and patches.
pgeodns is copyright 2001-2011 Ask Bjørn Hansen, Develooper LLC and licensed under the Apache License 2.0.