The GBU 28 "Bunker Buster" is a great demonstration of thinking "out of the box" and how the need to get it done can overcome the normal bureaucracy of weapons procurement. In January of 1991 US forces did not have a bomb in their arsenal that could penetrate Saddam Hussein's bunkers. In 17 days the combined efforts of Air Force Systems Command, Watervliet Arsenal in New York, Lockheed Aeronautical and Space Systems, and Texas Instruments produced the needed weapon.
Watervliet engineers used 8-inch surplus artillery tubes to create the bomb casing and matched the casing to a Texas Instruments' guidance package from a GBU 27. The team, thus, created a 4,700 laser guide bomb. Upon testing the bomb was shown to be able to penetrate 22ft of concrete and 100ft of earth. In fact during the sled test the bomb penetrated the 22ft of concrete and then continued on for 1/2 mile.
The first two bombs were delivered in theater on February 27, 1991. Since then the US military has continued to improve the ordinance package.