I heart Wikipedia: The United States order of precedence

I love this stuff:

The United States order of precedence is a nominal and symbolic hierarchy of important positions within the government of the United States. The order is established by the office of the President of the United States and can be changed by the President, though in practice it is fairly established and rarely modified. It has no legal standing (for example, it does not reflect the United States presidential line of succession), and is instead used to dictate ceremonial protocol. The United States Department of State is responsible for enforcing matters of protocol in U.S. diplomacy.

from http://en.wikipedia.org/wiki/United_States_order_of_precedence