Egg whites can be frozen as-is, and will lose only a little of their foaming power in the freezer. Egg yolks, however, need some special treatment to keep from becoming pasty when thawed. Thoroughly mix one teaspoon of sugar with each egg yolk before storing; this will keep the egg proteins fluid after freezing.
For the most flexibility, freeze whites and yolks individually in ice cube trays, then pop them into a larger freezer-safe container. Once frozen, they will keep for several months.
Do you have any tips for freezing egg whites or yolks?