I use a zebralight AA headlamp. Very small, especially if you ditch the original headband for a shoestring plus a cord lock. (Shoestring = flat, somewhat flexible and does not tangle).

I also very rarely wear it on my head. When camping I use it as a chest lamp. Being a very wide flood light I still get light where I need it as long as I'm sitting or standing. It still works as a headlamp for those few situations where a chest lamp doesn't cut it, such as reading while lying down.