Perhaps there's a law of marketing that states, "If you want to add to an existing product's gee-whiz factor, just alter that product so it lights up in the dark." Really, who wouldn't want glowing paper clips, or baby bottles, or ... automotive window decals? That's the theory behind Powerdecal, a device that mounts on the inside of your vehicle's window glass, then displays an illuminated image of your favorite sports team, university, or other group to which you wish to proclaim your unflagging devotion.

Each "decal" consists of a 4-inch circular graphic image, and a rear housing that provides backlighting via an LED light. The housing also contains light and motion detectors, so that once the power switch is flipped on, the light will only come on in the dark, and only when the vehicle is moving – once the vehicle has stopped moving for at least two minutes, the light automatically shuts off.

The device mounts on the glass via two adhesive-backed clips. It can slide in and out of them, should you wish to alternate between displaying different Powerdecals in the same location.

Power is supplied by three AA alkaline batteries, which are said to provide approximately 45 hours of run time. The designers of the product had originally considered using a solar-powered battery pack, which would have been a nice touch – as it is, it's doubtful that many people will diligently check their device's batteries, and promptly replace them as needed.

Logo images available include NFL, MLB, NBA and NHL sports teams, divisions of the armed forces and emergency services, American colleges, and the flags of several countries. The Powerdecal is available through the company website, for US$24.95.

View gallery - 6 images