Always use defensive driving techniques, but when a moment of humor is needed, use Road Defender. It doesn't do a lot. Basically when you press one of the buttons, a scientifically chosen set of beeps will play and the middle car will respond accordingly. It seemed funny during the couple of hours I spent writing it. Possibly the best application is amusing small children while on long car trips.
Adult use is optional.
Shield - Creates an imaginary shield around your car. Turn on before pulling out of the garage. Won't help much in a real accident, but the thought is nice. Cloak - Makes car invisible. Use when driving past work when you called in sick.