In a small saucepan on medium heat, reduce the balsamic vinegar until thick, to about one quarter of its original volume. Watch carefully as it can easily burn. Cut the gorgonzola cheese into 18 bite-sized chunks. Spoon a dab of balsamic onto each pita cracker. Top with Gorgonzola cheese and pear. Drizzle with honey and finish each appetizer with a blackberry.