Some examples of common egg replacements in baking include tofu, bananas, applesauce and commercial egg replacers, such as Ener-G. In baking, eggs function as a leavening ingredient, add moisture and help bind other ingredients together, so any egg substitutes also need to fulfill some of these functions.
You can use bananas and applesauce as egg substitutes because they add moisture to baked goods. However, they do not help baked goods rise, so you should add baking soda as well. Tofu is the best egg replacement in baked dishes such as quiches or fritattas. Commercial egg substitutes, such as Ener-G, are available at most large grocery stores. There are relatively flavorless and work best in cakes, muffins and cookies.