In reality, digital technologies create highly toxic "electronic junk" that fills landfills and uses up large amounts of energy, both during manufacture and everyday use. You could run the world's air transport system off the energy required for IT. And there are even more second-hand, "rebound" environmental effects. Traditional computers at least had the benefit of keeping us at our desks, but these days you can do just about everything from your iPhone or Blackberry. While it's great to work (or play) on the run, mobile devices encourage, well, mobility. The more you move -- in planes, trains, and automobiles -- the bigger the environmental impact.