Google's Carbon Footprint Project

Use the Carbon Footprint calculator to measure your carbon footprint and find out what practical steps you can take to make it smaller. On a personalised google page, you can track your progress, update your carbon-reducing actions and see a Google Map featuring the footprints and actions of everyone taking part. To share ideas, ask advice or find people in your local area to collaborate with, join the UK Carbon Footprint discussion group.

Add the "Carbon Footprint" tab to your iGoogle homepage!

Google also revealed these tips to make your office greener on their Adwords blog.
1) Turn off the lights in conference rooms after you're finished with a meeting.
2) Turn off computers when you leave for the day.
3) Bring your own reusable water bottles and coffee mugs to work.
4) Carpool with your co-workers.
5) Try duplex printing -- save paper by printing on both sides.

Here are some more ways in that Google is helping people go green!