Preheat the oven's broiler. Brush the slices of bread lightly with olive oil, and place on a baking tray. Toast under the broiler for about 3 minutes. Watch carefully. Rub each crostini with a garlic clove for flavor.
Place the tomatoes into a medium bowl, and drizzle with olive oil. Season with salt and pepper.
Place the crostini on a serving tray. Top each one with a slice of mozzarella cheese, cover with a spoonful of tomatoes, and garnish with fresh basil.