Since we'll be talking about hog production externalities on Tuesday, here's a short document from NRDC on livestock pollution.
Here is a cool article from Stanford that summarizes the results of a modeling effort related to the environmental externalities of meat production. I like that they discuss the need for interdisciplinary research and propose pricing policy to reflect the true (social) cost of production. That's Pigouvian taxation.
Here is a link to the research article at the Journal of Environmental Modeling and Assessment.
More on the topic here from FAO.
Here at the NYT
Here is a report from the Pew Commission that quantifies the external costs of hog production. The good stuff starts on page 18. (warning: graphics-heavy pdf file)