In baked goods, eggs are used as a binder, emulsifier, and a thickening agent. But what do you do if you are unable to eat eggs? Flax "eggs" are a great substitute for the real thing and they are very simple to make. Use one flax "egg" as a one-for-one substitute for recipes that call for up to three eggs. Flax "eggs" (flegs?) work particularly well in loaves, cookies, and cakes. If you find that your baked good is not rising as much with a flax "egg," increase the amount of baking powder in the recipe by 1/2 teaspoon.
Ground flax is often available in the grocery store, but it is very easy to make your own - and it's often fresher this way. Simply grind up flax seeds in a cleaned-out coffee grinder, a grain attachment for a blender, or even with a mortar and pestle.
(This recipe is the equivalent substitute for one egg)