Answer:
A substitute for egg whites is flax seed. It is often used by those who have allergies and vegans. You can find many recipies online using flax seed and there are also many cook books in local book stores with that also.
See related links for a list of suggested non-animal substitutes.
There are some powdered products that you mix with water. They are just dehydrated egg whites. Other than that, I don't think there is anything that will act like an egg white.