Geek Habitat

Cities mark Earth Hour today from 8 to 9 PM local time– a single hour of energy conservation.
Sydney, Australia, was among world’s first city to “go dark”:
First cities go dark for Earth Hour - CNN.com

Google’s home page is black to mark the event, today, as well.
Google - Earth Hour

Anyone can do this… turn off all your lights from 8 to 9 PM. Light up some candles — pretend it’s a power outage! — turn on the camp lantern, play some scrabble or Monopoly, look at the stars (if it’s not cloudy) or make up stories about the people that lived where you are, thousands of years ago, etc.

Source: CNN
U.S. cities go dark for Earth Hour
From Rome’s Colosseum to the Sydney Opera House to the Sears Tower’s famous antennas in Chicago, floodlit icons of civilization have gone dark for Earth Hour, a worldwide campaign to highlight the waste of electricity and the threat of climate change. full story