Arrange tomatoes on a cookie sheet (or sheets) lined with aluminum foil. Mix celery, onions, garlic, basil, oregano, and sugar together in a small bowl. Spoon about a teaspoon of mixture on each tomato slice. Sprinkle with black pepper to taste. Add blue cheese crumbles and Parmesan cheese to top of each tomato. Sprinkle Italian dressing over top. Cover with plastic wrap; refrigerate several hours. These will stay good for several days in the refrigerator.