Walt Mossberg reviewed the Dash Express earlier this week, an in-car slice of salvation for anyone that spends much time in the car.
What does it do?
...[E]ach Dash Express...becomes part of a network, connected to the company via the Internet. Each device not only receives and displays information, but transmits it as well, acting as a "probe," as Dash calls it, to measure local traffic speeds. This information is compiled by the company and then broadcast back to all other Dash units in your area, almost instantly painting streets on your map with color codes to indicate traffic speeds.
In other words, the Dash Express makes one's car a giving/receiving node on a traffic network, helping others while one is helped. It's an excellent representative sample of Tim O'Reilly's principle of the importance of data and of defaulting to collaboration.
Head over to Mossberg's full review for the nuances of the device. He tests it with just two nodes and finds that it does a great job even with limited adoption. Just think of how good it will be once thousands or millions of cars have the Dash Express on board?