Preheat grill to low heat.
Spoon out seeds from zucchini halves.
In a medium bowl, combine sausage, tomatoes and ½ cup Parmesan cheese; mix well.
Fill zucchini halves evenly with sausage mixture, pressing gently; sprinkle tops with remaining ¼ cup cheese.
Grill, covered with grill lid, 45 minutes or until sausage is no longer pink.