I also try to put parsley in every container. I've had the best luck with cherry tomatoes, like Sweet 100. Make sure you put the cage in right away, or they will soon be sprawling all over your deck or patio. Don't buy the patio tomatoes at the nursery. Maybe it's just me, but I think they are hard and tasteless.
Cucumbers do especially well in containers.
For years I grew the bush variety in clay chimney flues and harvested quite a few. My neighbor grows zucchini which also seems to produce well in pots.