… why don’t you use the idle processing power of your computer to help forecast climate change in the 21st century?  www.climateprediction.net is a screensaver that by definition only kicks in when your computer is not being used. It then uses your PC’s idle processing power to work on its own climate prediction model – one of many thousands being run with different parameters and assumptions by the millions of people running this software.
The download is all free and the site is easy to use; all you need to do is download the core software – called BOINC – and then decide which project to join – they even have one helping to analyse radio telescope data for signs of extra-terrestrial life!
This concept is known as “distributed processing” and chops up very large problems into smaller pieces that individual PC’s can work on.  When the results are accumulated together all of these different computers equate to the largest super computer on the planet.
This is one of those “things you can do today” that is free and easy and helps the planet.  And don’t worry about burning more power – your computer would be switched on anyway as you don’t turn it off when you stand up and go to make a coffee.  
And if you are really worried about the power that you use then why not switch to a 100% renewable energy provider like www.ecotricity.co.uk – where you can even sign up online!  They will change you over to electricity that is 100% guaranteed to be generated from wind power and it’s the next best thing to erecting your own wind turbine and solar panels, which are capital-intensive and slow to pay back.
And that means I have now mentioned two things you could do today!