From their web page, http://fas.org:
"The Federation of American Scientists conducts analysis and advocacy on science, technology and public policy, including national security, nuclear weapons, arms sales, biological hazards, secrecy, and space policy. FAS is a privately-funded non-profit policy organization whose Board of Sponsors includes 51 of America's Nobel laureates in the sciences."
...
"FAS combines the scholarly resources of its scientists with a knowledge of practical politics. As a non-profit organization licensed to lobby in the public interest, FAS is uniquely qualified to bring the scientific perspective to the legislative arena through direct lobbying, membership and grassroots work, and expert testimony at Congressional hearings. FAS is administered by its President, Dr. Henry Kelly who also serves as a senior staff member and director of research."


Aside from being an advocacy group for scientists, they are also a major provider of technowarporn. Would you like to know the lethal dose of Anthrax? It's there. Been looking for pictures of nuclear explosions? They have a whole gallery. Looking for more official DoD documents than you can shake a stick at? You better believe it.