Some useful links related to climate change and campaigning, in no particular order. This list is by no means exhaustive.
The Climate Camp homepage
www.climatecamp.org.uk

Intergovernmental Panel on Climate Change: All the UN material you could wish for.
http://www.ipcc.ch

http://www.climateprediction.net/ distributed climate change modelling

Earth First
http://earthfirst.org.uk/

People and planet: Student action on world poverty and the environment
http://peopleandplanet.org/

Friends of the Earth
http://www.foe.co.uk/

Network For Climate Action
http://www.networkforclimateaction.org.uk/toolkit/aboutus.html

Plane Stupid: Bringing the aviation industry back down to earth
http://www.planestupid.com/

Indymedia: independent news reporting
http://www.indymedia.org.uk/

The Greenwashing Index
http://www.greenwashingindex.com/index.php

Think a link should be added? Submit it to website [at] studentclimateproject.org.uk