Orange juice is by far and away the most popular form of oranges, but they're great as a sweet treat and can be used in cooking. Here are some of my favorite ways to use oranges:
United States Department of Agriculture National Nutrient Database for Standard Reference. "Orange juice, frozen concentrate, unsweetened, diluted with 3 volume water." Accessed October 22, 2010. http://www.nal.usda.gov/fnic/foodcomp/search//.