This Saturday 27 November (or Friday 26 November if you're in the USA) is Buy Nothing Day.
The official website says:
"For 24 hours, millions of people around the world do not participate -- in the doomsday economy, the marketing mind-games, and the frantic consumer-binge that's become our culture. We pause. We make a small choice not to shop. We shrink our footprint and gain some calm. Together we say to Exxon, Nike, Coke and the rest: enough is enough. And we help build this movement to rethink our unsustainable course."