This year we grew tomatoes and some spices, but we'll probably extend it to other vegetables next year.

I guess this is a good place to plug:

www.growingyourownfood.com

I'm not affiliated with it, but I've discussed by email with Frank G., the guy behind that site. I think he's doing a good job of documenting his projects and his "turning vegetarian and loving it" experience.

If you don't have your own plot to garden, check out this article about guerilla gardening.

What is guerilla gardening exactly? Many participants consider it to be the act of taking over small, vacant or abandoned plots of land in one's neighborhood and sowing anything from flower seeds to miniature tomato plants. Since the majority of these parking lot parcels, alley edges, planters, and urban plots are often uncultivated and overgrown with weeds, a number of socially-motivated gardeners and community members are secretly using these areas to grow attractive flowers or much needed food for neighboring residents.

We wrote something about Guerrilla Gardening:

http://www.treehugger.com/files/2005/06/guerrilla_garde.php

Despite only moving into my new house early summer, I still managed to grow tomatoes and runner-beans. Unfortunately my attempts to grow carrots and cauliflowers were foiled by the neighbours' cats, which decided that the freshly-sown soil would be great for digging in.
Still, I'm now enjoying a rather late crop of organic tomatoes and runner-beans. I've not grown enough to significantly affect the amount of shop-food I buy, but they certainly taste nice, and there's an absurd joy in popping out to the garden for fresh veg.

got space & sun but only grow sprouts (& herbs that I don't eat) cos there's loads of polluting traffic & construction around - don't wanna eat emissions. Have heard other stories fo people growing food in their city plots then getting soil tested & it's very toxic.

Anyone got any tips how to grow low-pollutant foods in high-traffic high-everything-nasty urban areas? a double-door hermetically sealed chamber perhaps?