I. Grant Databases for the Sciences.

Community of Science: a database of funding opportunities. Free, but registration required. 
GrantsNet: Funding opportunities through Health & Human Services and other federal granting agencies.
Next Wave: GrantsNet. Funding opportunities for the Biological and Medical Sciences 
TRAM Research Opportunities & Administration: various agencies, foundations, and associations.
Downloadable Forms from Many Federal Agencies.

II. Individual Sources for Scientists.

American Chemical Society: Petroleum Research Fund
Camille and Henry Drefyus Foundation (Chemistry)
National Collegiate Inventors and Innovators Alliance
National Institute of Health. See also NIH forms for AREA Grants & AREA Review Process.
NIH: Hints for Writing a Successful NIH Grant.
National Science Foundation. See also:
FASTLANE
NSF Grant Proposal Guide
NSF sample budget and narrative justification using current Trinity information. 
NSF advice on how to satisfy the Broader Impact criterion of your proposal.
NSF guidelines on how to write an RUI impact statement.