If you live in New York or San Francisco, you can take advantage of a new service that allows you to share a ride with neighbors who are going to the airport at the same time you are. Hitchsters works by matching you up with both a co-rider and a limo service that picks both of you up and takes you to the airport.
It's for folks who want the convenience of home (or office) pickup, but are willing to trade a few minor inconveniences (a random ride-along partner and a potential extra stop) for a 50% price reduction. As TechCrunch readers note, it's potentially creepy to get in a car with a stranger, but that's what you're doing when you get into a cab or limo in the first place.
Hitchsters plans to expand to Boston and DC soon, and to add other destinations besides airports.