Yahoo has a Carbon Footprint Calculator that you can use to see what impact you
and your friends/family are having on the planet. What's great about it is that one
can instantly make a plan and 'pledge' to offset their impact.
In measurable amounts of carbon you can decide to what degree you can
lessen your impact through simple and often easy choices.
Equally good, or maybe even better is that the site shows how many others are
making a 'pledge' and to what extent their positive accumulative effect will be.
Current count:
62,050 People are pledging to save 168,467 TONS of C02/yr
Which is equivalent to 125 not driving for about a year.