Lemon: Stir 1 tablespoon fresh lemon juice and 1/2 teaspoon grated lemon peel into batter.
Candy bar: Sprinkle with 1 cup chopped candy bars (3-4 bars) before baking.
Pumpkin: Mix 1/2 cup canned pumpkin, 1/2 teaspoon ground cinnamon and dash each of ground cloves and nutmeg into cream cheese.
Chocolate Chip: Stir 1/2 cup mini semisweet chocolate chips into batter. Sprinkle with additional 1/2 cup before baking.