Hugelkultur is a process using woody material, usually at the base of a raised garden bed, to improve soil drainage, hold moisture, and use up woody materials. The wood will break down and rot over extended periods of time, which creates a great home for fungi and bacteria to live in while they break down the organic matter in the soil, and leave behind their nutrients and blessing. The wood also acts like a sponge, soaking up tons of water. This is most beneficial, because in theory, you can drastically reduce the effort and resources associated with irrigating!
I must note that more research determines that woody material can rob the soil of nitrogen, but this can be overcome by using nitrogen fixing crops, such as legumes, buckwheat, and many other crops. Keep in mind that every soil condition is different, and everyone has access to different materials, so this is an experiment for us based on theory. Our plan is to use as much polyculture growing in the beds as we can, mixing many nitrogen fixing and other nutrient rich crops with our first food crops.
Hugelkultur suggests that a height of at least 3 feet will see the most benefits, and we've started somewhere in there. As we grow more soil and organic matter, the beds will grow taller and taller, and more nutrient rich, thus continuing to expand our growing area and production. My dream is a bed as tall as me someday (I am 5'6"), although I don't know how I'll harvest the top. :)