Here's a blog that discusses music and environmental concerns:
http://rockandecology.blogspot.com/. Check out the comparison of thrash metal bands' environmental awareness!
A post on Grist by Bill McKibben about environmental music.
A list of environmental songs
The Singing Climatologist
Captain Sea Level
Thanks to Richard Wallace, Ursinus College Environmental Studies program, for these links! A student in my Intro to Ethics course passes along this humorous video by Tim Minchin: