1. ProposalCentral: https://v2.ramscompany.com/. A convenient access to grant opportunities from some 20 government, non-profit, and private organizations.
2. The SPIN Database: http://www.infoed.org/new_spin/spin.asp. Updated daily, this commercial database contains information on approximately 11,000 different funding opportunities from some 1,200 different agencies. Over 4,000 are in health-related, behavioral, or biomedical fields. (You can also create a regular search profile at http://www.infoed.org/genius_live/create_new.asp.) Subscription access is granted through your academic institution.
3. ResearchResearch: http://www.researchresearch.com. A giant database of funding opportunities open to US researchers, including corporate funds, nonprofits and state sources. Individuals can get a subscription for $99 for the first six months and $199 per year after that (an offer that the site notes is only available through November).
4. The Foundation Center's resources for individual grantseekers: http://fdncenter.org/for_individuals/.
5. The National Science Foundation's funding page:http://www.nsf.gov/funding/.
6. The Department of Energy's Office of Science Grants and Contracts site: http://www.sc.doe.gov/grants/grants.html
7. The American Cancer Society's research program: http://www.cancer.org/docroot/RES/RES_0.asp
8. The Juvenile Diabetes Research Foundation's information for applicants: http://www.jdrf.org/index.cfm?page_id=103207.
9. GrantsNet: http://www.grantsnet.org. Funded by AAAS and HHMI, this is a searchable database of funding opportunities in biomedical research and science education for graduate and medical students, postdoctoral fellows, and junior faculty.
10. The GrantDoctor (and all the other invaluable resources) at Science's NextWave: http://nextwave.sciencemag.org/cgi/content/full/1999/08/27/1.