I like the light idea. Just a normal bulb with a green cover on it would work too.
One of those high output green LED's would be awesome however. There is room under the handle for a press-fit bulb housing, and there are power sources in the door, just hook it up so it's always on when the ignition is on. (Who cares during the day, and with a LED, it will last longer than the car does.) Even if you wire it to the lamp circut, as soon as you open your door, the lamps would come on, and your green LED would light up, allowing the passenger to find it.