So there's a new series set in the world of Avatar: The Last Airbender, set about 80 years after the end of the series. It follows the new Avatar Korra, as she sets out from her secluded and sheltered life of training at the hands of the Order of the White Lotus, and goes forth into a world of technological wonder and social and economic tension. The setting of Republic City is directly based upon New York City in the Roaring 20s.
It is fantastic and everyone who has seen Avatar: The Last Airbender should be watching it. Everyone else should be watching Avatar: The Last Airbender.