Many flavors of Breyers' original ice cream contained no corn products. They pride themselves on their simple recipes, so their lists of ingredients are usually short and readable. That's not true of their yogurt and their newer "Breyers Homemade" ice cream, however, so read the labels carefully.
Haagen-Dazs didn't have corn syrup in their basic mix, but seems to have changed recently. Their chocolate-covered ice cream bars were OK, unlike Dove bars and all the cheaper brands, but they might have changed too. I'll have to check again.
Ben & Jerry's ice cream varies along product lines and according to flavor. An employee at Ben & Jerry's home office was kind enough to prepare a list of corn-free flavors as of October 1994, which turned out to be mostly accurate. I've recently (August 1998) asked for an updated list, but haven't heard from them yet.
The flavors that passed a detailed inspection are:
Stonyfield Farm yogurt and frozen yogurt are uniformly free of corn products, but I don't know how widely they're distributed. Stonyfield Farm Yogurt is in Londonderry, New Hampshire, and their yogurt is very popular in the northeastern U.S. I've just now (August 1998) tried Stonyfield Low-Fat ice cream and was very pleasantly surprised. It's much lighter than premium ice creams such as Ben & Jerry's, but has an excellent texture, strong flavor, and none of the dryness that I dislike in Breyers.
An easy way to get corn-free yogurt in a wide variety of flavors is to buy plain yogurt (almost any brand) and mix in baby food. Baby foods are often single-ingredient, which makes figuring out the label much easier than for most prepared foods.