I'm going to recommend a book that isn't on 2012 per se, but nevertheless had a profound impact on me and stimulated my interest in the calendar and all things associated with it. It's a novel about the conquest of Mexica written from the perspective of Cortez’ interpreter Malinali Tenepal:

Feathered Serpent
A Novel of the Mexican Conquest
Written by Colin Falconer

"Malinali Tenepal is on a mission of her own. Inspired by the predictions of her late father, a prophet and astronomer, she seeks the legendary Feathered Serpent, who will set the native population free from the tyrannical rule of the Mexica and bring about a renaissance throughout the land. She is blessed and cursed with the certainty that she, Malinali, will be at his side when he comes to power.
www.randomhouse.com/catalog/...lay.pperl

I was fascinated by the perspective presented here: that Cortez was Quetzalcoatl - The Feathered Serpent - and did fulfil the prophecy largely because Malinali believed him to be. It was about how prophecy and belief intertwined to make things happen. Like 2012 :)

Loved this book.