In the Southern Air Temple Aang goes into the Avatar State. When he does, these temples lite up:
Southern Air Temple
Avatar Roku's Temple
Kyoshi's Shrine
Also, a temple lites up that we can tell is in a water tribe. But it's not in the South Pole, as we saw the lone village there, and it looks nothing like what we saw in the North Pole. And it isn't in a deserted or destroyed place, since there are people there. Is it just in a part of the North Pole we've never seen, or was it overlooked by the creators? Or could it be in a part of the world we've never seen before?