I think that if I had a fire escape or some sort of a patio attached to my apartment then I would give gardening a shot. Nothing too extensive, but perhaps some plants that would produce simple salads. Portland is a food-y type of place, so it's not surprising to see some urban gardens around the peninsula, as pictured below.
Portland blogger Broke207 tried a small garden this year. Although it sounds like a lot of work and I too would probably set my hopes too high, it seems like a good challenge and it has slightly inspired me. For now I will rely on Hannaford and the Farmers' Market. Feel free to post about your urban gardening experiences in the form of a comment!