I remember once, I saw a car in a car park and (excuse the way I explain this) it had a very thin, almost like a glass sticker above the rear view mirror stuck to the windscreen that was infact an alarm light that came on natually when you armed the alarm on the car, now I have seen a similar thing on a BMW which is just a blinking blue light.
Now this car I saw had a light just like this only it was a knight rider light, I have thought about doing something like this for years and wondered if anyone has done it or know how to do it and how to get the bits i need?