I don't think they all count as 'natural horsemanship' though... definitely not some at the bottom. I'm going to start with parelli and anderson as I can see they are the most popular here. Still new to everything..
Definitely Clinton Anderson's DownUnder Horsemanship book, Establishing respest and control for English and Western Riders, By Clinton Anderson and Amy Hendrickson. Such a great book! And let me know when you've finished that list...I could use a few recommendations!:)