The Department of Defense (DoD) maintains a vast amount of information. Information that most folks don't normally associate with Defense. 

Consider the following:

GPS

The Global Positioning System (GPS) is a space-based satellite navigation system built and maintained by DoD and is freely available to anyone in the world with a GPS receiver.  In addition to navigation, uses of GPS include precise timing for financial transactions, search and rescue, communications, farming, recreation and both military and commercial aviation.  GPS is operated by the 2nd Space Operations Squadron at Schriever Air Force Base, Colorado.

Weather Data

The National Weather Service was originally known as the Weather Bureau of the United States under the Secretary of War as Congress felt that "military discipline would probably secure the greatest promptness, regularity, and accuracy in the required observations."  While under the Secretary of War, it was part of the US Army Signal Corps.  In modern times, DoD developed and launched the first weather satellite, Vanguard 2, on February 17, 1959 as part of the US Navy's Operation Vanguard and now operates the Defense Meteorological Satellite Program which are the most sophisticated weather satellites in the world.  DoD also makes major contributions to global weather forcasting through the US Air Force Weather Agency and the Naval Meteorology and Oceanography Command.

United States River Traffic Information

In 1899, The US Army Corps of Engineers (USACE) was given authority over navigable waters of the United States.  USACE maintains direct control of 609 dams, maintains and/or operates 257 navigation locks, and operates 75 hydroelectric facilities generating 24% of the nation's hydropower and three percent of its total electricity. In addition, USACE inspects over 2,000 Federal and non-Federal levees every two years.  Information about the river traffic through USACE locks and dams is available at the Lock Performance Monitoring System.