amaretto: almond extract. as almond extract has a much stronger flavor, only use about ¼ of the amount of amaretto called for.
bourbon: a teaspoon or two of non-alcoholic vanilla extract
brandy: water is a common substitution but, depending on the recipe, cherry syrup (from canned cherries), white grape juice, and apple juice can be used.
champagne: any sparkling fruit juice will do here, such as apple, grape or cranberry juices. ginger ale also works well
coffee liqueur: espresso is a great substitution
cognac: pear, peach, or apricot juice works well
crème de menthe: to substitute for crème de menthe, spearmint extract is a good choice, or spearmint oil, which should be diluted with a small amount of water.
peach brandy: use the syrup from canned peaches. make sure peaches are canned in heavy syrup. peach preserves can also be used
port wine: grape juice,
red wine: cranberry juice, grape juice, tomato juice, even beef or vegetable broth.
rum: vanilla extract
sherry: apple, pineapple, and orange juices