Just about any vegetable can be grown in a container. It's about picking the right pot for the right plant.
Tomatoes need at least a five gallon container although I'd want twice that size, but leafy crops like greens can grow just about anywhere.
I love filling containers with lettuce and putting them right next to a pot of flowers.
Lettuce and other cool weather greens will produce in the container for six weeks or so and then I'll plant something that blooms.
If you don't have room for a big garden, or you just can't get out there anymore, try containers.