Pros: super informative
Cons: not updated very often
RealClimate is a great site - a climate science blog run by climate scientists. It's got great contributors like Gavin Schmidt, a climate modeler at the NASA Goddard Institute for Space Studies. These climate scientists do a great job making the science understandable, analyzing new important climate science papers, and debunking the global warming myths that keep popping up. I check it frequently - one of my favorite websites period!
The best source of science information is directly from scientists. When filtered through the media, scientific stories often get distorted and misrepresented, so I think RealClimate is an invaluable website. Not only is it climate science directly from the horse's mouth, but they also correct the errors made in the media.