[QUOTE=PetroDude]
1491: New Revelations of the Americas Before Columbus by Charles C. Mann
This covers more than just the Aztecs and Inkas, but it is a very readable summary of much of the new research/discoveries about the Americas.
[/QUOTE]
The book’s full of interesting stuff, presented in a somewhat scattershot manner. But I liked it a lot. And it’s a good springboard for further research.