The central Atlas system, *already* knows all the necessary information. If you check your probe details on the web page, you will see a field called «Internet Address», which will differ from «Local Address» if the probe is behind the NAT. So my idea was simply to set up a DNS server with a custom zone backend that looked up this information directly from the central database it's stored in.
As you already concluded, we have the data to make this happen. It also seems that some of you probe hosts would find it useful -- but for completely different reasons, not for Atlas functionality as such. I have to admit this was not in our planning, but we're willing to listen to what you need :) So one thing we could do is to allow hosts to opt in to some form of probe DNS registration: simple or obfuscated. We could put this on our todo list if there's enough demand. Please let us know if you'd like to use such a feature. Regards, Robert