Want to get a daily image fresh from space or hourly weather observations sent directly to your RSS reader? If so, you might want to browse the summary page on First Gov that details the agencies with feeds. The feeds available from the Census Bureau alone are more than many individuals track on their readers.
It is not until you dig a little that you can find all of the information that Uncle Sam makes available via RSS. Give it a whirl and you'll be surprised at what you find. I was.