Avego is looking to replace the thumb as the tool of choice for getting rides on the road. The service uses an application that runs on the iPhone and other mobile devices to help match drivers and passengers traveling in the same direction.

Avego is designed to augment public transportation, and save fuel by encouraging drivers to share rides. Most people driving during rush hour are alone in their vehicles, surrounded by empty seats that could be carrying passengers. Public transportation in the U.S. is inadequate. "The problem with most of us in the United States is that public transit goes from where we don't live to where we don't work," said Sean O'Sullivan, chairman of Mapflow, the company that produces Avego.

O'Sullivan demonstrated the service at the DEMOfall08 conference in San Diego.

The service is available first on the iPhone, but will come to other mobile devices.

Drivers and passengers sign up for the service, and run an application on their iPhones. Passengers run the same application, and stand by the side of the road. The iPhone's built-in location services let the service know where the drivers and passengers are.

The service observes which routes the driver typically travels -- from home to office, for example -- and lets the driver know when he's approaching a passenger going the same way. The service sends alerts using voice and a dialog box on the iPhone. Similarly, the service lets passengers know when a car is approaching that's going the same way. The driver and passenger use the iPhone app to let the service know whether they're interested in traveling together. If so, the driver pulls over and picks the passenger up and they're on their way.

When the trip is done, the passenger and driver let the service know, and the passenger pays the driver a pre-arranged price for the drive. The price is paid through the service. The driver can rate the passenger with one to five stars, and the passenger can do the same for the driver.

Drivers waste $3,000 per year on empty seats in their cars, O'Sullivan said. 80% of the transportation network is wasted. In an era of rising gas prices, society can no longer afford these inefficiencies.

The service will need to overcome several obstacles. First and foremost: Security. While hitchhiking was commonplace well into the 80s, people are afraid of it today, and putting a social-networking hig-tech face on hitchhiking isn't likely to make it less scary. Nobody wants to appear as the victim in a Web 2.0 remake of The Texas Chainsaw Massacre.

Furthermore, like many social networking services, it faces a kind of Catch-22: It won't be useful until it's popular, and it won't be popular until it's useful. If you're the only one in your county using Avego, you'll spend a long time standing out in the cold waiting for a ride.

And, even if Avego can overcome those obstacles, it faces one more: Commuters enjoy their solitude. For busy people with children, drive time is often the only time they got to themselves.

Still, if Avego takes off, it'll put a high-tech face on an age-old practice: Thumbing a ride.