Thanks for the suggestions, Mithalwen. I have a good start on my Container Jungle already with heather, philodrendrons, a few varieties of lily, and a jasmine vine, not to mention a fiercely overgrown ficus tree. I had thought about trying a fruit tree or some vegetable plants, but hesitated since my balcony is screened. Don't you need bees to cross-pollenate the flowers in order to get veggies? I've always had this weird fantasy of growing pumpkins on my balcony...
...but I don't think I want a colony of bees on my balcony!