The Carbon Bathtub: The Big Idea--Climate Control
The December 2009 National Geographic issue (print and online) has an excellent set of graphics describing the global system of carbon flow including sinks and fluxes with related climate change concerns. Using a bathtub with quantitative inputs and outputs, and the potential to overflow, this is a comprehensive visual description of a complex system.

Global Warming: It's All About Carbon
A funny, engaging, five-part animated cartoon series from Robert Krulwich and NPR that provides a basic understanding of the science behind carbon bonds, fossil fuels, greenhouse effect and global warming.