The focus on peer-to-peer room rental sets Airbnb apart from other accommodation-booking services are targets a different type of client.

FORBES: Airbnb's Explosive Growth Draws Big Cash (and a big valuation)

Preview Travel has a pretty cool Web site, mimicking a skilled travel agent right down to anticipating--based on where you have traveled in the past--the type of trip you are booking.

FORBES: Automating the Web

Mr Clarke's solution: customers booking a flight should be told more than the ticket price and the type of plane used on a route.

BBC: smokestack in Beijing

Air France offers obese passengers booking a second seat up to 33 percent off the ticket price, depending on the type of seat and availability.

CNN: Airline policies juggle larger passengers