Well, you make blueberry cake, of course!  My next door neighbor's grandmother picked blueberries in Michigan and overnighted them to Boston.  I was lucky enough to be given part of the precious shipment, so I put them to use in a blueberry cake.  Here's the recipe (from AllRecipes.com):
Melt In Your Mouth Blueberry Cake   "This is a nice tender cake - one of my Mom's specialties from years ago. It is a great cake to take along to a picnic." Ingredients: 1/2 cup butter1/2 cup white sugar1/4 teaspoon salt 1 teaspoon vanilla extract2 egg yolks1 1/2 cups all-purpose flour1 teaspoon baking powder 1/3 cup milk2 egg whites1/4 cup white sugar 1 1/2 cups fresh blueberries1 tablespoon all-purpose flour1 tablespoon white sugar Directions: 1. Preheat oven to 350 degrees F (175 degrees C). Grease and flour an 8 inch square pan. 2. Cream butter or margarine and 1/2 cup sugar until fluffy. Add salt and vanilla. Separate eggs and reserve the whites. Add egg yolks to the sugar mixture; beat until creamy. 3. Combine 1 1/2 cups flour and baking powder; add alternately with milk to egg yolk mixture. Coat berries with 1 tablespoon flour and add to batter. 4. In a separate bowl, beat whites until soft peaks form. Add 1/4 cup of sugar, 1 tablespoon at a time, and beat until stiff peaks form. Fold egg whites into batter. Pour into prepared pan. Sprinkle top with remaining 1 tablespoon sugar. 5. Bake for 50 minutes, or until cake tests done.