Fried tater tots with a drop of A-1 and sour cream on top---tastes like a fully loaded baked potato.
We like mozzarella cheese sticks with cocktail sauce instead of marinara, the horseradish and the cheese go very well together.
Banana baby food drizzled over sliced strawberries or used as a dipping sauce for whole berries is really good, too.
Ranch dressing on store-bought frozen pizzas.
Honey mustard sauce with french fries. French fries and hot fudge sundaes.
Sliced cucumbers on top of a saltine cracker with tuna fish salad (just mayo and pepper and salt) on top of the cucumber. It cleans up the fishiness really nicely. Tomato wedges on the side make it that much better.
Hard, stick pretzels with cream cheese that has a ton of garlic powder added to it.
And of course peanut butter and honey sandwiches!
I also like pickle sandwiches and tomato sandwiches---just slice, add mayo to the bread and throw it together.