Not only do tinted windows block 65 percent of the sun's heat and 99.9 percent of its damaging ultraviolet rays, but many think they're (like a couple other entries on this list) totally boss. Though most states ban windshield and front-window tinting, you can still have your back windows tinted.
But even if the law gives you the green light, be sure to weigh the perceived awesomeness of tinted windows against the danger before taking your car to the local detail shop. The risk of reducing visibility out your back windows is obvious -- say hello to sideswipes during lane changes. Less obvious, but no less dangerous, is the reduced eye contact with pedestrians and other drivers that tinting creates. How often do you wave another driver through a four-way stop, meet eyes with a pedestrian waiting at a crosswalk or use other types of sign language to signal your intentions and emotions to drivers around you? With tinted windows, you can kiss this communication goodbye.