AGPtek has come up an extremely cool product in the form of these Sound Activated Car Stickers. Others have nasty bumper stickers. You will have a dancing set of equalizer bars throwing vivid flashes of blue LED lights on the rear windshield. All you need to do to make it work is hook it up with a power source compatible with the 12V DC inverter you get with the package. The actual sticker is a thin sheet that comes with double-sided tape and a protective membrane. You simply remove the membrane and press down the sticker. Switch on the power and let the windshield bars do their thing. The dancing lights are hard to miss for drivers behind you, so these stickers also make it less likely that you’ll be rear-ended.