I had never thought of doing this, but know that I've seen it, I'm wondering why I hadn't. It seemed too true to be true, the endless possibilities of waffle flavors and sandwich fillings all combined. It's not like the bread, because you can easily and quickly make it and it can have different ingredients inside the waffle. I used my recipe for sour cream bacon waffles, and filled it with grilled chicken,cheese,tomatoes,lettuce, and my favorite (homemade) salad dressing. It was delicious, and it was really filling too, so I only used 1 waffle and used half for each side, although it would much easier just to make smaller waffles. This isn't really a post that comes with a recipe, just suggestions on waffle and filling combinations.
Sour Cream Bacon Waffles-Chicken,lettuce,tomato,cheese
Cornmeal Waffles- Eggs, cheddar, serrano ham
Wholemeal Waffles- Cream cheese and smoked salmon
Apple Waffles-celery, nuts of your choice,creme fraiche (or sour cream)
Plain Waffles- Add oregano to the batter,dried garlic,dried onion, and tarragon. Then top with balsamico,mozzarella, and tomatoes topping with fresh oregano if you wish.
This are not the world's most original, they already exist in sandwich and panakes varieties, and you can really put whatever you want and mess with all the different flavors you can come up with. You should make your waffles slightly crispier than usual(cook for longer) so it can hold all your fillings and toppings.