Other groups have created barter economies. thredUP specialises in exchanging children's clothes, but also has exchanges for everything from make-up to video games.

ECONOMIST: Schumpeter

But it also lets me make calls, log on to Twitter and Facebook, share photos, play games with friends and send messages through a variety of services.

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Its large screen will make it an attractive e-reader and video player, but it will also inherit a vast array of games and other software from the iPhone.

ECONOMIST: Tablet computing