Slice ciabatta bread in half lengthwise. Spread pesto on the cut side of each half. Top bottom half with slices of fontina cheese, and then place slices of tomato on top of cheese. Broil until cheese melts, and remove from broiler.
Place lettuce over tomatoes, and then position top half of bread on top of everything. Slice into 8 or 10 small sandwiches, and serve.