Zipcar or RelayRides. Want to buy or sell old possessions? Try Ebay or Craigslist. Need a loan but want an alternative to a bank? Try Zopa. Staying overnight in another city? Sure, you can rent a hotel, but now you can also use Airbnb or Couchsurfing.
What's Mine is Yours sums up the new universe of what authors Rachel Botsman and Roo Rogers term "collaborative consumption". The book, like the movement it describes, is a game changer, as the authors connect the dots and show how key systems (like redistribution markets and collaborative lifestyles), principles (like critical mass and belief in the commons), and drivers (like environmental and cost concerns) have all matured to the point where collaborative consumption is not only viable but may soon supplant traditional buy, use and discard consumption altogether.
You can read more about What's Mine is Yours and the collaborative consumption movement at http://www.collaborativeconsumption.com. I would also suggest that you go buy the book, but in the spirit of its message, I implore you to barter or swap for the book through one of the many exchange markets available today.