Consider joining an email LISTSERV or setting up an RSS feed to keep informed of funding opportunites at the NIH.
Both options update you on information from the NIH Guide for Grants and Contracts, the official publication for NIH medical and behavioral research grant information and opportunities.
Join the NIH Guide LISTSERV:
Send an e-mail to email@example.com with the following text in the message body (not the "Subject" line):
subscribe NIHTOC-L your name
(Example: subscribe NIHTOC-L Bill Jones)
This same information, and directions for how to unsubscribe, can be found here.
Set up an RSS feed:
Point your preferred RSS reader to http://grants.nih.gov/grants/guide/newsfeed/fundingopps.xml
More information can be found here.