Hugelkultur

Hugelkultur (or 'hugelculture') is the method of raised bed gardens where the practitioner buries wood with soil and compost. The wood serves as a means to retain water, thus reducing or eliminating the need for irrigation. The wood also provides nutrients to the growing vegetation as the material slowly breaks down.
Hugelkultur is nothing more than making raised garden beds filled with rotten wood. This makes for raised garden beds loaded with organic material, nutrients, air pockets for the roots of what you plant, etc. As the years pass, the deep soil of your raised garden bed becomes incredibly rich and loaded with soil life. As the wood shrinks, it makes more tiny air pockets - so your hugelkultur becomes sort of self tilling. The first few years, the composting process will slightly warm your soil giving you a slightly longer growing season. The woody matter helps to keep nutrient excess from passing into the ground water - and then refeeding that to your garden plants later. Plus, by holding SO much water, hugelkultur could be part of a system for growing garden crops in the desert with no irrigation.
Hugelkultur has been summarized by advocate Paul Wheaton:
*grow a typical garden without irrigation or fertilization
*has been demonstrated to work in deserts as well as backyards
*use up rotting wood, twigs, branches and even whole trees that would otherwise go to the dump or be burned
*it is pretty much nothing more than buried wood
*can be flush with the ground, although raised garden beds are typically better
*can start small, and be added to later
*can always be small - although bigger is better
*You can save the world from global warming by doing carbon sequestration in your own back yard!
*perfect for places that have had trees blown over by storms
*can help end world hunger
*give a gift to your future self
==External links==
Hugelkultur forums at Permies.com
Hugelkultur article at Rich Soil