Next time you’re stuck in traffic, take a look at the license plates on the cars around you. To a user of bump.com–which launches today–each one is like an email address that can be used to contact the owner, whether to tell them a rear light is out or that you like their bumper sticker.

“To send a message you just need to specify state and plate,” Bump’s VP of technology John Albers-Mead told me at the DEMO conference in Santa Clara, California, where the La Jolla, California, firm will launch this afternoon.

Anyone that has registered their license plate can pick up those messages while an upcoming smartphone app–initially for iPhone but later Android too–will use image recognition to make sending messages easier. When using it you simply snap a photo of a license plate after which it is processed in the cloud to direct your message appropriately. Initially you have to specify a plate to contact manually, or using an automated call-in service.

Developing the image recognition software wasn’t easy, says Albers-Mead, because different states use different styles and fonts on their plates. He and the rest of the bump team have been using the retired police cruiser below to test the software’s abilities. When hooked up to a collection of cameras and infrared lights on the cruiser’s light rack the software proved capable of identifying up to five plates a second even at freeway speeds.

Using license plates for a novel communications network may sound like fun, even if Bump will surely have to deal with problems like spam. But the firm also says that being able to recognize license plates and message a car’s owner could has the potential to be of serious interest to businesses.

“It allows us to track users, it’s like putting a cookie on a car,” says Albers-Mead, likening his technology to the small files used to track web users and offer functionality like autologins online. Once connected up to Bump’s tech, a camera at a store or drive-in burger joint could, for example, showing menu choices similar to those you’ve selected before. That extra data could be valuable to store owners, Bump say, who could also make use of the messaging functions. “You could register as a fan of the Dodgers and then receive a message welcoming you to the stadium and offering discount vouchers when you visit,” says Albers-Mead.