Practical Currency

Normally, your money is not inherently useful. Sure, you can melt down coins and make them into some sort of art project, or you can try to use your paper money to start a fire, but for the most part, money only has value because people agree that it does. The moment people lose faith in it, money will be worth nothing.

Not so with Practical Currency. You can actually use it for something. Maybe it's some kind of food, medicine, or weaponry. It's not too different from a barter economy—it's still goods in exchange for goods and services—but unlike barter, it also serves as a universal medium of exchange (people who don't need the item itself will still accept it because they can trade it for something else) and a universal measure of an item's value.

In the real world, there is commodity money. Not all commodity money is practical currency, however: gold, for example, until very recent times has very few not entirely decorative uses—mostly, tableware—but made good commodity money because it is pretty, rare, but not too rare, and does not corrode.

Weird Currency is a Super-Trope; Energy Economy is a Sub-Trope.

Examples of Practical Currency include:

Anime and Manga

In Ghost in The Shell Stand Alone Complex one episode took place at a "wine fund" where wine was used as an investing or a speculating vehicle, since it is difficult to reproduce synthetically and increases in value with age. Not really currency, though.
The metabugs in Dennou Coil. Useful for making programs to muck around in cyberspace, and as such to playful kids they're quite the commodity.

Comic Books

In Hex, the post-apocalyptic re-skin of Jonah Hex, the standard currency are Soames: pills used to decontaminate radioactive water.
Water in Tank Girl
In Bone, residents of the valley use things like eggs and livestock as currency. Phoney finds this out when he tries to spend Boneville dollars and gets some very dirty looks.

Film

In the Elvis Presley film Jailhouse Rock, his prison mentor is the richest man in prison, with hundreds of cartons of cigarettes in his cell.
In Mad Max 2, car fuel (usually gasoline) is the only reliable currency.
Kin-dza-dza! has matchsticks (made of natural wood and sulfur) useable this way on Pluck.
In In Time, time from one's lifespan is used as money.

Literature

Metro 2033 (and video game) - ammo is used as money everywhere
Much discussion of this in Making Money, including pointing out that gold is worthless on a desert island, that it's also worthless in a gold mine (where the medium of exchange is the pickaxe), and the contrast between what happens when you bury gold vs. when you bury a potato. Oh, and in the end they decide to base the currency on golems. The idea of paper currency started in the previous book, when people began using postage stamps as a means of exchange.
- Commerce in the villages of Lancre, where hard currency is a rarity, is more likely to be negotiated in chickens than in coins.
Water on Dune itself and Spice everywhere else in Dune.
In the Uglies trilogy, "The Smoke" community uses instant food packs as currency, which makes newcomer Tally quite wealthy by the community's standards.
Iron in Sergey Lukyanenko's Seekers of the Sky, made so because of its rarity (It Makes Sense in Context). A character even mentions using gold for currency, only for another character to say that, while gold is valuable, it doesn't have a lot of use. Of course, you better keep all your iron bars in a dry environment.
- There is a scene where the protagonist sees a flagship of The Empire with its sides gold-plated (to show off, not for armor). He muses that they could've easily afforded to iron-plate the entire ship, but it would, of course, rust at sea.
Mistborn has fairly standard coinage, but it's also the go-to weapon for steelpushers, to the point that steel mistings are called coinshots.
- And this coinage is backed by Atium, an ultra-rare metal that gives Mistborn the ability to see a short distance into the future. While having your economy be dependent on a substance that gets regularly used up may seem like a bad idea, Atium seems to be renewable, and the people who own the mine are very rich, even after the Lord Ruler takes his cut.
Another Sanderson example, from The Stormlight Archive: The currency is spheres, tiny chips of gemstones encased in marble-sized glass balls. But they're not valuable because they're gemstones, but because the gemstones can act as magical foci for various things, particularly Soulcasting (transmutation magic.) Diamonds are the least valuable, because they have the least useful Soulcasting property, whereas emeralds, which can be used to turn stones into food, are the most valuable denomination.
In Dinner at Deviant's Palace, the prevailing currency in a post-apocalyptic California is alcohol. It's a fuel, a disinfectant, and a beverage as well as money.
In Gene Wolfe's Book of the Short Sun series the inhabitants of the Whorl (a giant Generation Ship at the end of its journey, now orbiting a pair of potentially-inhabitable planets) have taken to using circuit boards as currency due to their scarcity. This of course means that the ship's already-strained technology is failing rapidly, and the theft of boards from the ship's few operational shuttles means that soon there'll be no way out for those who haven't already left.
In Gordon R. Dickson's Childe Cycle, the interstellar currency is largely based on skilled professionals. If a planet needs someone or something, they hire out a specialist in exchange. The economy of the Fourteen Worlds is based on the trade of contracts, which not only affects political decisions, but also drives the plot of several stories.

Live-Action TV

In the TV series Love And War waitress Nadine is an aging socialite whose husband is in prison from the Savings & Loan scandal of the early Ninties. At one point she mentions she's going to visit him and bring 2 cartons of cigarettes in order to buy him his way out of his latest Noodle Incident.
A side comment by a Free Jaffa merchant in Stargate SG 1 suggests that naquadah is used as currency, or at least a standard of measuring value for barter.
- It would have to be a specific kind of naquadah. Weapons grade naquadah is extremely dense, as shown in an episode where two Jaffa (who are much stronger than regular humans) are carrying a weapons grade naquadah brick the size of a laptop. Daniel, being physically enhanced by an alien artifact, knocks out the Jaffa and stashes the brick into his backpack, having no trouble carrying it (why the backpack didn't rip is not clear). When the effect of the artifact wears off, he has to dump the naquadah in order to even walk. There is also the liquid kind.

Tabletop Games

Dungeons and Dragons
- 2nd Edition Maztica Campaign boxed set. True to the style (see below), the Mazticans use cocoa beans and ears of mayz (corn) as money.
- Giff in Spelljammer use smokepowder as currency and prefer to be paid in it.
- Dragonlance steel coins.
Deadlands: Hell on Earth: Although the game itself uses dollar values for convenience, it mentions that most places operate on a barter system and any spare 'cash' the characters have is usually in the form of easily transportable luxury items. Or bullets.

Video Games

Gothic: In the penal colony, magic ore is used as a currency. It is supported by the fact that the outside world desperately needs this ore and is ready to give food, booze, and hookers in exchange for it. You can also find coins, which unlike most objects have zero value.
In some of the Sonic the Hedgehog games, rings are often used as a currency. Rings have had practical uses (such as protection) since the beginning of the series.
System Shock 2 has nanite packs as a basic exchange unit.
Guild Wars uses gold and platinum for its official currency, but characters can only hold 100 platinum on their person at any given time: enough to buy anything from an NPC, but nowhere near enough for trades in the player market. Thus, the de facto currency is ectoplasm, chosen for its use in crafting rare armour. It's measured in "globs" and is bright pink.
- In a similar manner, the Diablo 2 community used certain well-known "rare" items (well, they drop rarely, but given the size of the playerbase there are still tens of thousands of them) such as the traditional Stone of Jordan ring as currencies. Though each trade was effectively a barter, valuable items would have an agreed-upon market value in, say, Stones of Jordan or Zod Runes.
Metro 2033 uses pre-apocalypse bullets as currency, they produce noticeably more damage than the regular stuff, but then you would be literally throwing away cash.
Souls are the standard currency in Demon's Souls and its spiritual successor Dark Souls since they are a source of great power. Some unlucky people in Demon's Souls actually need souls to exist since they (like yourself) are already dead and need souls to keep their own souls from fading away.
Kingdom of Loathing is some kind of an example, since its currency is Meat. However, since it's currency, you can't actually eat it. However, you can make that Meat into paste to combine items with and into stacks to smith equipment out of.
Freedroid RPG uses Valuable Circuits. Other than in trade, you can obtain them from hostile robots and use to upgrade items.
In Shin Megami Tensei: Strange Journey the expedition the player is part of quickly discovers the demonic currency can be converted to energy which can power their replicators. This explains why No Hero Discount is in effect despite the player quickly coming to lead the expedition. The demons do not appear to realize their currency can be used this way however.

Web Comics

In Escape from Terra the primary medium of exchange on Ceres is grams of gold but water certificates, cokens (issued by the local Coca-cola bottling plant) and Grubstake Units are also mentioned. [1]^{[dead link]}

Western Animation

At least a couple Transformers continuities have Energon as both a currency and... Cybertronian food, I guess?

Real Life

Ancient "coins" frequently were goods spontaneously promoted to this role by the barter economy just because they are compact and valuable. Such as knife billets or small furs. Precious metals became universal the same way, but mostly for decorative value.
Some countries use cell phone minutes as currency.
Colonial Virginia (at least) used tobacco as a form of currency.
Real life ancient Mexicans like the Mayans and Aztecs used lengths of woven cloth and cocoa beans as currency. Therefore the rich could afford drinks like xocolÄ�tl (where we get the word Chocolate) more often. People even made counterfeit cocoa beans out of clay.
Cigarettes are a common form of currency in prisons.
- And in the occupied Berlin in late 1940's.
- In some prisons where tobacco is banned or hard to acquire, prisoners use postage stamps instead, since they're not only legal but are small, easy to carry and have a small round price.
Vodka was often used as money in Russia during the Nineties crisis. Sometimes still used, mostly in remote areas.
Salt was used as currency in Sahel. And in the Roman Empire. This is where we get the term "salary", and the saying of being "worth one's salt".
Tea bricks were used as currency in some parts of ancient China.