Elemental Evil and Dark Sun
Today Wizards of the Coast released the Elemental Evil Player's Companion. This is more or less a set of character races and spells. What Dark Sun fans will be interested in is the races, Aarakocra, Goliath, and Genasi (there's even a sidebar entitled Genasi on Athas) as well as a slew of elemental themed spells.
So if you're playing Dark Sun with D&D 5th edition, this is a must own....and it's free!