i've got a few 9" deep pots and i've put carrots in them, you can sow them as normal and eat teh wee ones when you thin them out and then get a few bigger ones left to grow in teh pot
things like peas are good for pots as they grow vertically, so put them up a wall or fence
Courgettes would do well in a pot on a windowsill - loads of food of one good plant!
if you can get a wee plastic cold frame type thing, i'd highly recommend an apache chilli plant - i got hundred of chillis of one on my kitchen window sill last year.
buy some of the bigger compost bags and throw some seed tatties in and stack the bags up against a wall. though maybe not ideal if space is tight