My favorite links:
News
Government
C-Span: for those of you who can't get enough of politics and government
Federal Government: a great starting place to find information about and by the federal government
White House: the White House's website
Department of Homeland Security
GlobalSecurity.org: a non-profit defense policy group
Reference
Reference Desk: reference links including dictionaries, encyclopedias, almanacs, etc.
Thomas: Congress' website sponsored by the Library of Congress