Welcome to what's called "collaborative consumption" with Internet companies like Airbnb, RelayRides, Liquid Space and TaskRabbit. They're providing access to things you want without the burden of ownership — cars, houses, tools, garage space — even leftover food. They're building a marketplace that's already worth $26 billion, reducing waste and throwing a scare into business based on consumption. But what about safety, regulation and trust? Is this the future or only a fad?