Hi John,
Right off the top of my head, I thought peppers. Peppers cross fairly readily in close distances so isolating a variety in the greenhouse would well. Plus peppers grow well in pots. You could also do eggplant.
I'm drawing a blank on anything else right now(long day at work!) Most of the other veggies I grow get large and do best in the ground. Maybe someone else will have a suggestion.
Remy

Thanks for the reply remy. I see few if any insects or bees of any kind in the GH. I would probably have to pollinate with a Q Tip. I am certain they would do better in the ground but if I would get a few smaller fruits, it may be worth wile.

John

Here is a link that might be useful: John's Journal

Hi again,
I got good news for you. They don't need insect pollination! : ) They do get pollinated by insects, but as long as they get movement, by wind, or shaking them, they will develop fruit. Not all vegetables are like that. Tomatos, peppers, eggplants, beans, those are the popular ones with perfect flowers. Perfect is the name for when a flower can fertilize itself.
Remy