Sites that have evidence for global warming ( Again, I acknowledge climate change, though I am uncertain of what degree of significance our actions will have) :

The scientific consensus on climate change: http://www.sciencemag.org/cgi/content/full/306/5702/1686

The EPA's information page:
http://www.epa.gov/climatechange/

Borderline propaganda found in Google search for "global warming":
http://www.climatehotmap.org/