Zipcar is the most expansive company that facilitates car-sharing. Car sharing is really cool…basically, I guess, it’s as simple as it sounds (I just realized I don’t really know the details of it). You either don’t own a car yourself or don’t own a second one (more often the former, I think), and just use one of these shared cars when you really need one. But anyway, Zipcar is expanding, increasing its size in the Bay area, and starting up in Chicago.