I finished Under the Banner of Heaven by Jon Kroger this past weekend, and while it is a good book and one I would recommend to others, I would also caution anyone reading it to approach Krakauer's writing style with a grain of salt. The man is not a subtle author, and his opinion is laid plain for all to see. He also has a tendency to present two disparate things in close proximity to each other, so that the two become entwined (and nearly synonymous with each other) in the reader's mind, regardless of their real world relationship. Specifically, he will write paragraphs detailing some aspect of the Mormon religion, and then launch into some frightening tidbit of Fundamentalism with nary a break. While true that there would be no Fundamentalist Mormon faith without the mainstream Mormon church, the two are not nearly so closely linked as the book may make them appear.
Also, the descriptions of murders, and other behaviors, in several chapters are the stuff of nightmares. Especially for an atheist.
However, out of all the information the books provides, the two neatest tidbits that I came across are that two companies that are household names started out as religious communes.
Oneida started life as a commune in Oneida, NY in 1848, and then reformed as a joint-stock company when the commune broke apart in 1881, though it wasn't until the second decade of the 20th Century that Oneida began to focus on silverware.
The second company is Amana, originally Amana Refrigeration, and was founded in 1934 and wholly owned by the Amana Society until 1950. And while the Amana Colonies are no more, the church still seems to be a vital part of the local community.