Gandi http://www.gandi.net/ has a pretty good reputation, with free DNS hosting. No IPv6 reachable nameservers, however. If you want IPv6 reachable DNS servers, Hurricane Electric offers free DNS hosting https://dns.he.net/; they are a big supporter of IPv6 and so offer a variety of free services to help get it off the ground.
thanks, I'll give Gandi a try with my next domain. I am using some free services from Hurricane Electric, particularly an IPv6 tunnel and also a dynamic DNS after dyndns.com pissed me off.
for production domains, I would still prefer a DNS hosting that is somehow paid for (with godaddy it was included in the registration price).
