Hugelkultur -- the German technique of creating a rich growing environment. Just bury a bunch of logs, brush, sticks, etc. with regular soil, add some compost on top, and you have an awesome grow-anything environment good for at least 5 years!
You won't need to water it, fertilize it, or till it during all that time.
I'm going to try this myself, as soon as time permits. Hopefully in the next couple weeks.