Submitted to Fey Parrill's Cheeseblock challange (and disqualified for some silly essay length reason...)
Most items in the U.S. Army serve multiple purposes. Jerrycans were used as bricks in World War Two, cooking pot lids as ping pong bats in Vietnam, rubbers as anti-sand filters for gun barrels in the Gulf Wars, and tin hats as pretty much anything since time immemorial. This is usually attributed to the ingenuity of soldiers. However, there may be more to this, as recently declassified documents describe a DARPA project that tried to make every piece of standard army issue serve at least three distinct purposes.
Project Leatherman was led by Colonel Damyu J. Mudpuddle, a former physics professor, janitor and vacuum salesman (in that order) with a peculiar talent for filling gaps where no-one knew there were gaps. Often, there were indeed gaps, which is why some viewed Mudpuddle as God, or at least the Pope. However, there were not always gaps, which is why most viewed him (Mudpuddle, not the Pope) as a moron.
In hindsight, it is clear that the military had yet to come to grips with the notion that failure is part of the creative process, and just as unclear how the project lasted as long as it did.
The project produced two notable products in its three month lifespan. The first was the Zoppi lighter. This was a non-toxic liquid that, when poured on a backpack, made it lighter. Unfortunately, this was because it made a hole in the bottom of the backpack. It eventually earned a name among soldiers as The Liquid Can Opener and the only thing that would be relied upon to destroy such incriminating evidence as memos, litter and used anti-sand filters.
The second product was the cheeseblock. This had a number of uses, 96 at last count. Most were what any sensible person would do with a brick-shaped object, such as throwing it at enemy troops when the ammo gave out, dropping it on rural huts, or breaking windows in jewellery stores during invasions. It could float, and many a life was saved by a cheeseblock raft. The fact that its smell kept sharks away didn't hurt, unless your sense of smell was actually working at the time.
Cheeseblock had a high albedo, making it an excellent reflector at night. Several soldiers, desperate to get injured so they could go home early, used it to provide an easier target for the enemy to hit. As it was bullet proof and thus very useful as a shield in trench warfare, it could hardly be banned.
Best of all, in the words of an obscure technical report, cheeseblock "becomes edible, with a unique, cheese-like flavor, when heated". The appendix of the report goes on to qualify these terms. 'Edible' means that lab rats forcefed with the stuff did not throw up (more than half their body weight) or die (within 24 hours). 'Heated' means 'heated for 37 hours at 370 degrees Farenheit'. 'Unique' means what it says, fortunately.
Thanks to a clerical error, samples of cheeseblock made their way to the general public, sans instructions. Records of the public response to this remain classified, though it is unlikely that our nation's mighty bowels were ever tested, owing to our nation's not-so-mighty teeth.