A friend sent me an email, asking me to sign on to Earth Hour 2008 with her, then turn off my lights at 8pm on March 29. Curious, I followed the link, and this is what I found:

It started with a question: How can we inspire people to take action on climate change?

The answer: Ask the people of Sydney to turn off their lights for one hour.

On 31 March 2007, 2.2 million people and 2100 Sydney businesses turned off their lights for one hour - Earth Hour. This massive collective effort reduced Sydney's energy consumption by 10.2% for one hour, which is the equivalent effect of taking 48,000 cars off the road for one hour.

With Sydney icons like the Harbour Bridge and Opera House turning their lights off, and unique events such as weddings by candlelight, the world took notice. Inspired by the collective effort of millions of Sydneysiders, many major global cities are joining Earth Hour in 2008, turning a symbolic event into a global movement. -- Earth Hour website