If you are wondering how to obtain vital records, then the National Center for Health Statistics is the best place to start. Every state is represented here, with detailed information on how to go about getting what you need.
Whitehouse.gov not only gives you the latest Presidential news, but you can also find out the President's official stand on a whole plethora of policy issues, from budget management to national defense.
Ben's Guide is an excellent introduction to the US government: "This site provides learning tools for K-12 students, parents, and teachers. These resources will teach how our government works, the use of the primary source materials of GPO Access, and how one can use GPO Access to carry out their civic responsibilities."
Need to apply for social security benefits? Replace your Medicare card? How about plan your retirement, qualify for disability, or get help with name changes? You can do all these things and more at Social Security Online.