"The new "Grants.gov" system, under development at a cost of tens of billions of dollars, aims to replace paper applications with electronic forms. It is being phased in at the National Institutes of Health, Department of Housing and Urban Development and other federal agencies. All 26 grant-giving agencies are supposed to have their application processes fully online by 2007."
Editor's note: NASA opportunities are also present on this system - but the accuracy of the information leaves something to be desired. Have a look at this announcement for the Mars Telecommunications Orbiter which was cancelled last year.
Reader note: "The University of Wisconsin has released a standalone package for using Grants.gov on Mac OS X as a service to the community. The package uses Citrix client software and a special settings file to access the central Citrix server provided by Grants.gov, allowing users to access and use the PureEdge software via the remote Windows machine running Citrix server software: http://apple.doit.wisc.edu/grants.gov/"