Sorry my post double-posted --- don't know why.
Anyway -- here's a recipe from cooks.com that is close to what I use:
ROYAL ICING (Egg White Recipe)
3 egg whites, room temperature
1 lb. confectioners' sugar
1/2 tsp. cream of tartar
Combine ingredients, beat at high speed for 7-10 minutes. Yields less volume than royal icing made with meringue powder.
Royal icing is a hard drying icing. Please keep covered with a damp cloth. Humidity will greatly effect this icing. Both icing recipes are excellent "glue" for Easter Eggs, gingerbread houses and cookies you want to dry hard. Grease will greatly effect this icing. Be sure to wash all utensils with a good dish soap.