The National Institutes of Health (NIH), The main links relevant to grantseekers for the world's largest granting agency.
National Science Foundation (NSF) plus main links relevant to grant seekers for NSF
Fulbright Scholar Program (Dept. of State, Council for International Exchange of Scholars), Funding for research and teaching abroad as well as to bring international scholars to the United States.
(Dept. of Education), Funding for current and future U.S. educators in
language and culture.
Grants.gov is a web-based single submission portal developed by the federal government. It provides a searchable database of most federal grant opportunities. It also provides a mechanism for applying for federal programs. When fully operational, this promises to be the one stop site for all federal funding information.