If you can find them, use fire-roasted diced tomatoes (such as Muir Glen); just add a pinch of basil, a pinch of oregano, and a minced garlic clove. Feta doesn't melt, but baking makes it creamy and spreadable. Toasted sourdough bread and rosemary focaccia are also good accompaniments.
1 teaspoon fresh lemon juice
1/4 teaspoon crushed red pepper
2 garlic cloves, minced
1 (14.5-ounce) can diced tomatoes with basil, garlic, and oregano, drained
Combine first 4 ingredients in a bowl. Sprinkle feta evenly into a 6-inch gratin dish or small shallow baking dish coated with cooking spray. Top with tomato mixture. Bake at 350° for 20 minutes. Serve as a spread with bread slices.