I ran across this design recently. Many of the contributors have a small stream flowing near their cabin. It seems to me, this type of pump would be a natural ("money for nothing and chicks for free" kind of thing). There's only two moving parts and no power.
http://www.youtube.com/watch?v=4oEJ6pygCHU&feature=related
Utube has quite a few clips, including building one.
I'm a lurker and thought this might be a way to pay my way!!
A very cool old invention that I have seen in a few different configurations. It is a good free water source under the right conditions. w* to the forum.
interesting, thanks for posting the link