Vanilla ice cream for me. I never eat it except when I have an upset stomach.
Cliche, but chicken noodle soup and saltines always work for me.
Thanks for all the great suggestions! I feel much better today, but still don’t have much of an appetite. I cooked up some chicken noodle (Lipton, not campbell’s) and had a piece of bread too (never been a “toast” guy). I also had some gatorade when I got to work this morning.
My standby is egg-drop soup if I can manage to go get it. If not, I settle for saltine crackers with maybe some peanut butter, or toast. The ginger ale option is great settling your stomach.
Tapioca or rice pudding. Assuming you like them when you’re not sick. 
Me, too. Except even when I’m sick, it’s a snap to make a very plain one at home.
Ingredients: one can of broth, one egg. Heat the broth to boiling in the microwave while you beat the egg, then slowly pour the egg into the broth, stirring slowly. Voila, instant egg-drop soup, and it’s plain and easy to digest when you’re a sickie.
I vote for not eating something you rather like when you’re not sick. I can’t stand most chicken soups, because I associate it with the Campbell’s I only eat when I’m completely wretched. (Bland, salty and my husband can cook it.)
Strangely enough, I and many people I know like to have a spicy broth when feeling ill. I had a gf who would ask me to make one of those spicy ramen noodle packages whenever she was feeling queasy so that she can have some of the fiery soup.
I’ve been known to make garlic soup for a cold or flu, but I don’t think I’d want it if I were feeling queasy.
(Whole head of garlic simmered in a quart or so of water with sage, peppercorns, parsley and a dollop of olive oil. Salt to taste, strain and enjoy. You can do the egg drop thing with it, too, if you want.)
I eat mashed potatoes and drink warmish water when I’m sick.
I’ve heard great things about ginger ale for this problem, although our family’s standby was 7-UP.
I’ve also heard saltines advised to pregnant women with morning sickness to settle the stomach.
I’m glad others have mentioned eggs, because I was afraid I would cause hurling with this:
My favorite comfort food when sick as a child was a slice of toast with butter, cut into one inch squares, and mixed into a bowl with a chopped up soft-boiled egg (white kind of solid but yolk still runny) with a sprinkling of salt and pepper.
Absolute heaven when you’re watching Captain Kangaroo and trying not to puke into the roasting pan on the floor by the living room couch on a school day.