The Hungarian Forint is used in very large quantities ($1 USD = 218 Ft) so the government recycles a few tons of it every year. After shredding it and bundling it into bricks, the currency is shipped to charitable organizations to help with their heating cost.
Deviant Artist Midnight Angel put together an arm blade stylized after the ones used in the Assassin's Creed video game series. Using a drawer opening mechanism, a spring for a screen door, and a throwing knife, the weapon works surprisingly smoothly. The full instructions are on Angel's page, and you can see it in action below.
I've seen photos of this thing floating around for a while, but never did it occur to me that it's in fact a real product. Available from Hammacher Schlemmer, this Wenger tool holds the Guinness Word Record for being the most multi-functional penknife. Kudos to you if you can name all of its fucntions. If not, here's a real Swiss guy going over how ridiculous this thing really is.