Here are some links you may find helpful:
US based site, with a calculator and further information on climate change.
Carbon Gym webpage
Aimed at young people, so easy to understand - possibly oversimplified in some places.
Earth Future article
Article suggesting ways of reducing your footprint (website based in Canada).
Fairly detailed website aimed at reducing individuals' carbon footprints.
Carbon Footprint site
Footprint calculator does not take some aspects into account, and list of ways to reduce footprint is not quantitative, but basic info is accurate.