You can pull a car uphill with just a piece of rope, and a tree
From Lifehacker …
How To Pull A Van Uphill (with Only A Rope) - video powered by Metacafe
This video shows one of the simplest machines, the pulley–not a lever as Lifehacker says–and how it increases your ability to lift/pull heavy things.
If you want to try this at home … try something other than a car … log or something.