What are they, and what do they actually do? I'm sure a saw a footballer being given smelling salts recently, and I'd always thought they were an old fashioned sort of thing.
I think they're supposed to smell so noxious that it instigates an inhalation reflex response, thus helping you regain consciousness (or helping prevent you from falling unconscious). I think it's the ammonia that does it, phew-ee!
Using Smelling Salts can be dangerous if the person has a probability of a neck injury, as they often make people snap back their heads to get away from the smell. If a neck injury was present then it could lead to complications.