Here's a neat Instructable for significantly increasing the geek factor in your car's rear windshield, showing how to modify a Wi-Fi-detecting t-shirt into a Wi-Fi-detecting window decal. At some point in some traffic jam, you'll make a fellow nerd's day.
Starting with a novelty t-shirt that displays the strength of Wi-Fi signals in the area, an Instructable user lived up to his matching user name and license plate of "MacGeek" by hacking together this Wi-Fi detecting window decal.
While it may not be entirely useful for finding access points, except maybe to a laptop-wielding driver behind you in a serious bumper to bumper, it will definitely be useful for announcing your geek pride to your fellow drivers. [Instructables]