Egg-whites are great when added to ground beef (for making hamburgers or meat loaf). It is virtually undetectable but reduces shrinkage dramatically, helps the ground beef hold together better (binds the meat), and gives you a more juicy end product.
Egg-whites can also be used for the same purpose in stuffings(dressings), that is, to bind the other ingredients together. And if you don't know what to do with good stuffing, let me make a suggestion; Beef roulladden. Take a flat piece of beef and pound thin and even with a meat mallet. Spread the stiffing onto the meat and jelly-roll it together. Tie it with butchers string before baking so that it holds its shape. Can you say Yum?
Use them to make bread puddings, or mix with water and brush over pie crusts, pastries, and breads to give the crust a glossy finish.
You can use egg whites to add protein to soups, as in egg-drop soup, or scramble in a hot pan with some minced garlic, mushrooms, and olive oil (the eggs will absorb the other flavors), then add to stir-fries.
For lighter french toast, scrambled eggs, etc. add the extra egg whites to whole eggs before beating.
Beaten egg whites are the glue that you brush onto fresh pasta before sealing the edges of won tons, egg rolls, spring rolls, ravioli, etc. It keeps the pasta edges together during the cooking process.
Use a combination of whipped egg whites, cornstarch, powdered sugar, and vanilla to make your own marshmallow cream. Egg whites are used for making the nougat found in the center of many candy bars. I have a recipe at home for this. And many candy fillings are made with egg shite. Do a google search and you will be amazed at what you can easily, and inexpensively make.
Raw egg whites freeze very well so that they can be used when needed for any of the above ideas.
I'm sure that you can see from this short list I've provided, that you can get very creative with egg whites.
Seeeeeya; Goodweed of the North