Heat oil in a skillet over medium-high heat. Add capers, and sauté 3 minutes.
Rub garlic halves on both sides of bread slices. Coat each side of bread slices with cooking spray. Arrange bread slices on a large ungreased baking sheet; broil 40 seconds on each side or until toasted.
To serve, top each bread slice with 1 basil leaf, 2 slices tomato, and 1/2 teaspoon capers. Drizzle evenly with balsamic vinegar.