We have a box of mini Shredded Wheat in the house which the 13yo occasionally has for breakfast but none of us are big fans of cereal. He would happily have Coco Pops or something like that but we don't approve of that kind of thing.
We're all big fans of eggs, though. Poached, boiled or scrambled usually. Sometimes with a bit of bacon, maybe a grilled tomato.
Actually, grilled tomato on toast is rather good for breakfast (cf pizza, as mentioned earlier).
Granary toast with peanut butter and/or marmalade is another personal favourite. Or Marmite.
If you have time, pancakes are excellent for breakfast. To save time, you could make them the night before and reheat them. Or even have them out of a packet.
One of my specialities is oaty bacon and egg pancakes - make a pancake batter with oats instead of flour and add bits chopped up bacon to the mix. The pancakes come out quite thick, more like blinis than crepes, so are quite portable too - you can take them with you if you have to rush off.
d.