In a large bowl, combine the flour, 1 cup sugar, baking powder, salt and ginger. In a small bowl, combine the eggs, buttermilk, oil and lemon peel. Stir into dry ingredients just until moistened. Fold in rhubarb. Fill paper-lined muffin cups two-thirds full. Sprinkle with remaining sugar. Bake at 375° for 20-25 minutes or until a toothpick inserted near the middle comes out clean. Cool for 5 minutes before removing from pan to a wire rack.