Other than being able to tell left from light, turn indicators and those red brake indicators (and those ridiculous center mounted third brake lights, thank you Elizabeth Dole), tail lights have had a 'creative design' side, which seems to become more noticeable at various times. Most recently the advent of LCDs has stimulated design, since LCDs come as minimal bitty lights which are then mounted to form various rows & columns, or for the whimsically inclined, patterns. I've found the Jeep designs, which are diagonal crosses in circles, most noticeable.