Americans Against World Empire, Americans Against Bombing
Conservative/libertarian coalition opposed to military imperialism and particularly the blockading and bombing of nations who have done the US no harm. Regularly updated, news analysis.

Anti-Intervention Network
Coalition of groups and individuals who oppose all U.S. military intervention, anywhere in the world. Mission statement, calls to action, membership information, and directory of participants.

Antiwar.com
News, viewpoints, activities, and articles on various flashpoints around the world. Archive available.