So like 1% of the Federal government (by spending, just making this number up) is going to be closed.

National parks, EPA, WIC, and Housing and Urban Dev.

99% of the federal government (by spending) will remain open, including:

US Military, Food stamps, Unemployment benefits, Social Security benefits, TSA, air traffic control, border patrol, Federal Reserve, and the Post Office.

http://www.npr.org/blogs/itsallpolitics/2013/09/30/227884483...