For the early morning classes I teach, I usually just have coffee or a very large "fountain" diet coke. (I don't like soft drinks from a can or bottle, picky, picky, picky).
If I'm just dying to eat, it's usually a small bowl of cheerios and milk, nothing heavy.
Does anyone else use "sugar free" instant breakfast instead of protein shakes? I drank a lot of protein shakes when I was competing, but they were expensive. And never tasted good, either. But now for a quick snack, I'll sometimes have a sugarfree instant breakfast made with skim milk (and sometimes a banana blended in). There's some protein in the milk, and lots of vitamins in the instant breakfast.