I was browsing through When Violence Erupts: A Survival Guide for Emergency Responders (I can't for the life of me, find the original mention of this book) and I came across this self defense technique:
While conducting drills at the Maryland State Police Glen Burnie Barracks, Trooper First Class (TFC) Raymond J. Beard taught a technique that successfully disrupted the chain of events in an intended shooting incident 12 out of 12 times (Maryland State Police In-Service Training School for Trooper First Class, 1983. Maryland State Police In-Service Training School for Officer Survival, 1987). A state police instructor sat in the driver': seat of a stopped vehicle. When asked for a driver's license, the instructor drew a weapon and squeezed the trigger in a simulation of shooting the approaching trooper. TFC Beard told the troopers participating in the exercise that if something came out of the vehicle at them, they were to take off their Stetson' with their left hand (driver-side approach) and throw it at the eyes of the person behind the wheel of the stopped vehicle. The intent of this action was to make the armed person blink or flinch. Throwing the hat was 100% effective—in each case the person with the weapon either misfired or misaimed. When something is coming at you, your initial instinct is to blink or flinch.
Consider what happens when you are driving during a heavy rain and a passing vehicle throws water on your cart windshield. Even though you know the water is not going to hit you, you still blink or flinch when the water strikes the windshield. This is the reaction you want to provoke in your assailant. Throwing your vitals pad at the person provides the same distraction as the water hitting the windshield or the troopers throwing their hats. It interrupts the chain of events long enough to permit you to get out of the line of fire and run to safety. Carry the pad In your left hand when you make a driver-side approach. When in position behind the Back Seat column, raise the pad to your left shoulder. If the vehicle occupant takes aggressive action during your initial interview, be prepared to throw the pad directly at the aggressor nose.
Use only a soft pad of paper for this technique. A hard object such as an aluminum report book or clip-board may cause needless injuries to the occupant of the vehicle. The soft pad will not cause undue harm. If the person is reaching for a lighter instead of a weapon and you react by throwing the vitals pad, you only have to apologize and explain. Exaggerate if necessary; say you just returned from a call where the patient took aggressive action toward you, and you thought it was going to happen again. After you throw the pad, do not wait for a reaction. As soon as it is out of your hand, turn to your right (toward the unit), get out of the possible line of fire, and run to safety. (p26-27)
Pretty clever, no?
The above technique talks about pretty specific conditions: approaching a vehicle and either being a police officer or an EMT, and triggering a distraction with either a hat or a vitals pad (which is effectively a spiral notebook). But, I'm thinking this approach could be generalized in any number of ways. It's certainly one worth having in the back of your mind, when you find yourself in an encounter your not 100% comfortable with.