Organizations

• American Association for the Advancement of Science 
• American Society of Mammalogists (my primary organization)
• The American Institute of Biological Sciences 
• Association for Biology Laboratory Education (ABLE) has great links to a diversity of resources.  A wonderful group!
• Biolab Home Page is the web page for the Biolab discussion group.  It's got archives of discussions and more ideas about teaching than any one person (except some of its great teachers) can probably accomodate in a lifetime.
• Coalition for Education in the Life Sciences 
• Center for Undergraduate Research 
• National Association of Biology Teachers 
• Professional Societies and Organizations in Natural History is the place if you're looking for a society but don't know how to find it.