It just kinda depends on my mood. Sometimes I like bacon, cheddar, Velveeta, celery, and onion. Other times call for lightly saute'd sliced mushrooms (white button for this one), a good sage flavored pork breakfast sausage, and either a good, sharp swiis, or milky smooth muenster cheese.
Sometimes I want just diced ham and American Cheese.
I also love diced, fresh tomato with grated Parmesano or Asiago cheese and a touch of sweet basil, with a scant drizzle of EVOO.
I've even been known to add cinamon and Splenda to the beaten egg, and fill with breadfast sausage, and Velveeta cheese, all covered in maple syrup (french toast without the toast).
You can litterally fill omelets with almost anything. Try combining ground beef with canned tomato (dice or crush the tomato). Add just salt and pepper and freshly sliced onion. Cook until the onion is tender. Use together with Jack or Mozerella cheese as the omelet filling.
Bucky, I think you're gonna like this one, especially if you can smmother it in hot sauce. Another favorite in restaurants around here is a combination of Swiss Cheese, hash-brown potatoes, sausage, bacon, mushrooms, and onion.
I'm fond of a good home-made corned beef hash, seasoned with S & P, to be used as a filling, and all of it topped with ketchup (I know, yikes!).
All you need to do then is say, yum
Seeeeeya; Goodweed of the North