python starting point: http://code.activestate.com/recipes/491264-mini-fake-dns-server/
c starting point: http://lordikc.free.fr/wordpress/?p=829
ruby start point?: http://half-penny.org/computing/simple-ruby-dns-server
perl start point ... *vomit*: http://www.net-dns.org/

potential language-agnostic solution: http://doc.powerdns.com/pipebackend-dynamic-resolution.html