Elaine’s Peanut Butter Cookies (Courtesy of AllRecipes.com)
1 (18.25 ounce) package yellow cake mix
1 cup creamy peanut butter
1/2 cup vegetable oil
2 eggs
2 tablespoons water
1. Preheat oven to 350 degrees F (175 degrees C).
2. Pour the cake mix into a large bowl. Make a well in the center, and add peanut butter, oil, eggs, and water. Mix [...]

Source: “Perfect Light Desserts,” by Nick Malgieri
These are absolutely delicious AND lower in calories than the traditional cookie recipe. Visit this post for a detailed review and pictures.
David’s Skinny Chocolate Chip Cookies
1 ¼ cup all-purpose flour
1 teaspoon baking soda
½ teaspoon salt
4 tablespoons unsalted butter, softened
½ cup light brown sugar, firmly packed
6 tablespoons granulated sugar
1 [...]