The NIH has announced today (03/24/2017) that it will now allow Investigators to cite their interim research products (Preprints, software etc) in Progress Reports, Grant Applications, and Proposals.
The NIH recommends that Investigators use pre-print repositories that are robust and allow the pre-prints to be easily findable, accessible, interoperable and reusable.
A good example of such a repository is biorxiv.org
For more information the NIH guidance can be found here
Reporting Preprints and Other Interim Research Products