Substituting one ingredient for another should only be done when you don’t have the necessary ingredient on hand in your kitchen. Substitutions can change the flavor and outcome of the finished baked goods.
The following charts in the links below give substitutions that may be used to achieve a product similar to the original when cooking. Find out what to substitute when you're out of an ingredient - but also remember the following when substituting:
When substituting ingredients, take into account the differences in taste, moisture content, texture and weight.
When substituting for sugar and flour, consider the differences in sweetening and thickening power.
Understand the physical and chemical properties of all ingredients.
Measuring accurately will help avoid disappointment.
Common Ingredient Substitutions Article - Allrecipes.com
Baking and Cooking Ingredient Substitution Chart, Whats Cooking America
And if you looking for healthier alternatives:
Sensational Substitutions for Cooking and Baking | SparkPeople