Gardening in small spaces

I had a conversation with my mother and father in law a few days ago where we talked about using rice bags as gardening containers. Our yard is very limited in space, the soil is very poor and thin, and pots are relatively expensive. I'd previously looked up the square foot gardening method, but saw no practical way to put it to use here (wood planks are relatively expensive and don't last long anyway between the heavy rains and the termites). So the suggestion to use rice bags was an intriguing one.

Then someone else pointed me to this link about bag gardening. In this video - it's short and very much worth watching - a young girl plants a small garden in a 50 or 100 kg rice bag or equivalent therof. The bags that I have are only 5 or 10 kg rice bags, which are a nice size for me to deal with, and are woven from nylon or plastic or some such, so won't degrade quickly.

So. I'm going to start rice bag gardening. Okay, so my mother in law got me started by planting a pot full of gotakola (a very useful plant in terms of nutrition and health benefits).

Our next door neighbors have a couple dozen rice bags filled with plants lining the back of their house, two bags deep. So, you know, it's not just me or my mother in law.

What do you do to garden in small spaces? What would you like to grow?