There are many people who work on this way. I will put some links to their pages.
Natural Horsemanship is a way of working with horses. It' a human way to tell horse that you are his friend and that you wan't him to be partner with you. It's much easyer to work with horses, and much easyer to accomplish whatever you want...
In the fall I was working with my horse Prince everyday, using Clinton Anderson's training method. He was really improving, but now that it is so cold, I don't work with him anymore.(well I sometimes I go and take a little bareback ride in the pen when it's a little warmer.)
I combine alot of peoples natural horsemanship into my own. My friend though, serious Parelli gal, she loves it, I cant wait until Parelli comes to utah this year, my friend, the barn owners and I are all planning on heading down there to see him, my friend is so happy about it!