We use PowerDNS for one of our new domain name. We plan to use the geo backend of PowerDNS to provide some geo-targeting feature and automatically redirect our fellows users to the closest server available. This was quite easy to setup. Once you have found a good PowerDNS administration tool (such as pdns admin), this is much easier.
Let's wait until this go in production (first website is http://www.macmillandictionary.com)!