I know that avocados are supposed to keep longer with the stalks; I would like to know if it is also true for tomatoes?
Removing the stem from a tomato opens up a hole where air, moisture, and bacteria can pass through. Keeping the stem in, or somehow sealing the "scar" from the stem, will prolong shelf life.
(Published in Cook's Illustrated - requires subscription - http://www.cooksillustrated.com/howto/detail.asp?docid=1173)
The tomatoes may continue ripening if you keep the stalks in.
Yes, leave the stalks in. It was by accident that I discovered this works. I was in a rush and I picked a bunch with all the stalks attached. By the time I got home one was knocked off. It turns bad much faster. So I purposely did it again, with the same results. Once the stalk dries out, that’s when I notice the tomato starts to turn. Sometimes I had them for a couple of weeks to my surprise. If you would have told me, I wouldn’t have believed it.