No, there isn't. Trust me, I have looked all over the internet for these, as I have done the DNS exploits for Gens 4 and 5 multiple times. If there is, it is probably very private and only accessible to a handful of people.
if Nintendo ever shuts down 3ds wi-fi connectivity, (which probably won't happen in the near future, dear god don't let it happen,) then there is a good chance that some DNS servers for Gen 6 and 7 events will pop up.
Hope I helped