Zimride, a website that aims to connect people looking to drive intercity routes, seems like a perfectly good idea for a business. You've got a car driving from L.A. to San Francisco with room for an extra passenger, I've got a need to get to San Francisco and a desire for a cheaper option than flying. Enter Zimride. Good idea.
But they're making their East Coast debut with a New York to Washington route, which seems to me like one of the least promising business opportunities. Not only is there a lot of plane and train service on this route, but there are a ton of intercity buses connecting the Big Apple to the capital. The main downside of the buses as opposed to the more expensive options is that they tend to get stuck in a lot of slow traffic, but ridesharing has exactly this problem as well. It's more expensive than the bus, but in important respects offers less service—buses have onboard bathrooms and many have Wi-Fi and other facilities.