I'm not much of a gardner/farmer. Okay, okay, I'm not good at either but I am curious to learn more. My yard, once you get past a thin layer of soil, is slate. I learned this the hard way the last time(s) I have had to plant some ex-pets. I would have to build up above the normal layer to grow anything substantial, that foot by foot idea looks good.

I've been curious about Hydroponics. I was looking at the Sky Mall recently and saw a set up in there for growing tomatos "upside down", not sure if it was hydroponic related.

I heard an idea years ago, I have never tried it, nor have I seen anyone else try it, but it's a space saving / recycling idea that sounds kind of neat, collect some discarded tires, fill a tire with soil, nutrients, etc. and plant potatos in it. ( may work for other root veggies, not sure ) Repeat this with each tire stacking them straight up. At harvest time you simply take a tire off the stack and shake your harvest out of it.