Science.gov
A federal information portal for a wide range of science-related materials. Includes funding opportunities, though they are sometimes difficult to locate. Interesting for browsing and for familiarization with agency activities/interests/priorities.
http://www.science.gov

NSF Custom News Service
Subscribe through the National Science Foundation's MyNSF at:
http://nspires.nasaprs.com/external

UniSci
Daily university science news service selects stories based on their scientific importance.
http://unisci.com/aboutunisci.shtml

GrantsNet
Funding opportunities for the medical and biological sciences, sponsored by the American Association for the Advancement of Science and the Howard Hughes Medical Institute.
http://www.grantsnet.org

NASA

• NASA Acquisition Internet Service (NAIS). Provides customized e-mail alerts for NASA procurement announcements. Primarily contracts, this system also allows you to specify notification of announcements from specific NASA centers:
  http://prod.nais.nasa.gov/cgi-bin/nens/index.cgi
• A unified web site for access to all research solicitations issued by NASA HQ program offices is available at:
  http://research.hq.nasa.gov/research.cfm
• The Office of Space Science (OSS) may be accessed through the menu listing “Research Opportunities” on the OSS home page at:
  http://spacescience.nasa.gov
  • Subscribe to the OSS research solicitations alert service:
    http://science.hq.nasa.gov/

National Institutes of Health

• NIH Guide for Grants and Contracts
  This is the official publication for NIH medical and behavioral research grant policies, guidelines and funding opportunities. For a weekly table of contents by e-mail, subscribe at site below or send message: “Subscribe NIHTOC-L your name” to LISTSERV@LIST.NIH.GOV. Leave subject line blank. Delete any auto-signatures or business card attachments from your mail message.
  http://grants1.nih.gov/grants/guide/index.html
• Centers for Disease Control and Prevention
  E-mail newsletter subscriptions:
  http://www.cdc.gov/subscribe.html
  Online listing of funding opportunities:
  http://www.cdc.gov/od/pgo/funding/grantmain/shtm

Environmental Protection Agency
The U.S. EPA Office of Research and Development, National Center for Environmental Research site allows you to sign up for a variety of e-mail lists, including one for grant opportunities.
http://cfpub.epa.gov/ncer_list/elists/

U.S. Department of Energy Department of Science

• The grants and contracts Web site is available at:
  http://www.sc.doe.gov/grants/grants.html
• DOE Pulse, a newsletter from the DOE National Laboratories, is available at:
  http://www.ornl.gov/news/pulse/pulse_home.htm#reminder
  (complete the "Remind Me" section at the bottom of the page to receive an e-mail link to new issues)

National Institute of Standards and Technology (NIST)
An information site for researchers is available at:
http://www.nist.gov/public_affairs/grants.htm

Subscribe to online information services and e-mail newsletters at:
http://www.nist.gov/public_affairs/mailform.htm