How about various size pots? I have a friend who gardens on her small balcony - she grows tomatoes, cucumbers and squash along with a lots of flowers - all in flower pots.
An old bookshelf or plant shalf will give you vertical space for multiple pots.
CRocks shoes are what I'm gonna do. I saw a pic of using them as planters hung on the walls!
Thanks for all the input y'all.