One idea is to cut them into chunks, process briefly in the blender, and simmer until they thicken into a sauce. Add meat or vegetables and serve over pasta. You can also use this sauce to top pizzas.
My favourite way to use surplus tomatoes is to make Italian bruschetta. It's good with crackers, but it's excellent on fresh French bread, topped with a little mozzarella cheese.
3 cups chopped tomatoes
1/2 cup chopped red onion
1 Tbsp fresh basil (or 1 tsp dried)
2 large cloves garlic
1 Tbsp red wine vinegar
2 Tbsp olive oil
salt and pepper
Mix all ingredients together. Allow to sit for several minutes before serving.