If you want to save some money on that overpriced taxi fare, check out Hitchsters, the new service that will match you up with another traveler so that you can split the cost of a taxi ride.
The service, in beta in New York right now, tells people with similar travel plans what each other's cell phone numbers are so that they can coordinate their rides. It's smart about its connections. For trips from the airport into town, for instance, it will match you only with people from your own flight (otherwise, flight delays would probably make it useless).
I'm in favor of anything that both reduces travel expense and cuts down on pollution, but nonetheless I have a problem with this program. The system doesn't vouch for its users, so you have no idea who you're going to get matched up with. The only thing you can state on the service is a gender preference. There's no "not a psycho killer" box.
Also, a friend--a New Yorker, in fact--said this to me when I told him about the product: "You're kidding, right? This is really a whole company?" I'm not sure it is, actually, since on the site's FAQ, the answer to "How does Hitchsters make money?" is, "We are still trying to figure that out."
Still, in many cities, New York in particular, a taxi ride to or from the airport is a very big expense. If you want to make an adventure out of that part of your journey, as well as possibly save some money, give it a try. Also check out Airtroductions, which will try to find you a better seatmate than the one the airline issues. And see my old column "Stuck in the middle with who?" for more travel tips.