Here are some useful sites:
Project Vote Smart
Sierra Club Endorsements
The Center for Responsive Politics
Candidate general biographical and campaign contact information. This site also reflects the results of redistricting. It also includes links to your state's election web site.
Wild Card - ratings of Senators and Representatives on protection of wild places.
The American Wilderness Coalition (AWC) web site for more information on protecting wilderness.
See AWC's Election Page for links to other groups with information on specific candidates.
EPA's Greenhouse Gas Database: This is a database of the top greenhouse gas emitters in the U.S. It is comprised of manufacturing and energy companies, among others.