Federal Material
This library is a congressionally designated depository for U.S. Government documents. Public access to the government documents collection is guaranteed by public law. (Title 44 United States Code)
The federal government makes and collects information on a huge variety of topics. The collection below is only a small sampling of what is available.
Getting Started
https://www.archive.org/details/FedFlix
Joint project between the National Technical Information Service and Public.Resource.org - although NOT at a "GOV" site - containing "over 3,300 films created by the US Government over the past 70 years". All are in the public domain and thus may be used for and by anyone.
Income tax information and forms, along with other taxation topics
Collects and organizes historical documents and records of the federal government
Portal to government resources for college students, including financial aid and career planning.
Career
https://www.careeronestop.org/
Sponsored by the U.S. Department of Labor, this site includes tools for job seekers, students, businesses, and career professionals
Criminal Justice & Legal
https://www.loc.gov/law/help/guide.php
A collection of links and guides on state, national, and international law.
The best place to find actual numbers on crime and crime-related topics.
"Justice and substance abuse information to support research, policy, and program development worldwide." Also available is the NCJRS Abstracts Database - does NOT contain (free) full-text.
Science & Medicine
The absolute best place to start for health and medical information, run by the National Library of Medicine. And the NEW Interface makes finding material and information even easier.
Information on most diseases, with focus on public health/prevention.
"Gateway to over 50 million pages of authoritative selected science information provided by U.S. government agencies, including research and development results."