In 2010, there was an Apple thing called Wide-Area Bonjour, which was an extension of mDNS (a.k.a. RFC 6762) on top of publicly-visible DNS servers so that you could have resources (presumably non-NATted IPv6 resources) running with well-known global hostnames.

I got really excited about it and worked on a little server program for it, as well as a publisher daemon called wamupd (code on github). As far as I know, the protocol died years and years ago and all this code is dead, but in case you're interested in archaeology, well, here it is.

My notes from the time are at *nix Tip of the Day: Dynamic DNS and Dynamic DNS: Part Two.