If you go to www.squarefootgardening.com you will find the work of Mel Bartholomew and supporters. Mel used to be in the US Army (don't hold that against him, he's incredibly open and sharing) and devised a raised garden bed system where you divide your garden into 'square foot' blocks, and plant accordingly. The medium is described on Mel's site, basically a 1/3 1/3 1/3 combo of vermiculite (couldn't find it here; used coarse pumice, works fine), compost and peat moss (I used pea straw, and apart from a few stray peas initially that's worked fine too).
There's some fantastic examples from Mel's site of how square foot gardening operates in all different parts of the world. You can buy his book here (I got one through a local Home Show for $30) but really all the info you need is on the website. I got the raised garden made by a local builder, purchased through Trademe, though Mel recommends all kinds of recycled options but he doesn't know my building skills (grin). It's covered with protective cloth using some recycled metal uprights ($8 total for 6 from a metal recycler's, around 7 feet high) so the butterflies etc. can't get in. It looks like the Day of the Triffids in there, with tomatoes, peas and beans gone mad. Do take a look at the site if you're interested in this form of gardening, which works well with no digging, and regardless of your soil.