The EarthHour website is struggling to maintain service as it's hit by a huge amount of traffic - I really like the idea - it won't save a huge amount of energy/emissions in itself but it will make people think about their impact on the environment and hopefully take action.
The idea is that each of us turns off as many (of our own) electrical devices as possible between the hours of 8pm and 9pm today - the 29th of March. If you are "late to the party" and are reading this afterward then you can still join in the spirit of things and do so another day.
I used to live in an area that experienced fairly frequent power outages - the rarely lasted more than a couple of hours - they made me realise quite how much I rely upon electricity.
Google have an excellent temporary replacement for their homepage which links to many interesting places including the Climate Savers Computing Initiative. They have "turned the lights out" on their home page for an hour - it's amusing me that the UK site has gone dark already and it's 75 minutes before the alloted time!
I was surprised to read that apparently the power utilisation of most monitors doesn't vary significantly regardless of what they display. I guess the majority of power from modern flat screens goes on the backlight which will be common regardless.