I add a dash of salt and pepper... and sometimes some onion and garlic powder. In a perfect world, I'd also add some sautéed onion and broccoli... but that's usually too much work for me.
I love adding cheese to my omelets, but stopped doing that a while ago as part of a general plan to cut back on dairy. Omelets without cheese are like a PBJ sandwich without jam. It's just so sad...
What do you put into your omelets?