I've only ever seen enemies drop cards of any sort in Maple Story and maybe Kirby. Where else has that been implemented?

Really, I think the only pertinent thing I had to say with this blog is that The Bard's Tale is pretty funny.

That is a terrible title. Why am I starting an article with.. oh hey there! Since I discussed dungeon crawlers (or the hybridization thereof) last time, I figured I'd move onto how games of this genre (and its other RPG contemporaries) allow players to interact with the treasure they find, specifically focusing on the relative merits of simple convenience vs. in-depth inventory micromanagement.
 
RPGs are all about the treasure right? Well, alongside the character development, strategic combat and those fanservice parts where the female protagonists put on bathing suits at the hot springs because Yosuke is a horndog. Mostly treasure though. To the extent that even if the developers are deliberately concentrating on the aforementioned characters/battles/jiggle physics, they still need to be mindful enough of a player's inherent desire for shiny things to have an extensive system in place for the acquisition and management of same.
 
So in this article I'll explain the general steps games take with their inventories and treasures, citing particular examples that either try something unique or just happen to have a particularly good/bad system in place. Starting with inventory systems:
 
Inventory - The Inventory wiki page adequately covers the three basic types of item management: The "Unlimited" system, usually employed by JRPGs and games less committed to realism over player convenience, the "Weight Allowance" system that limits a player's carrying capacity based on a physical characteristic often favored by the type of WRPG that is based to some extent on curiously pro-jock D&D encumbrance rules, and the basic "Fixed Capacity" system that limits a character's inventory to an arbitrary fixed number, usually represented visually as a series of boxes filled with each collected item - this system is the most often employed by video games on the whole, including games outside the RPG genre such as Dead Space or Resident Evil 4. This system of box-filling occasionally goes a shade too deep into some kind of abstract Tetris puzzle game, which makes me wonder why someone hasn't built a Tetris game with Diablo's weapon and armor sprites as a joke. Possibly because most people talented at coding don't have the free time that I do.
 
The Bard's Tale - In this sixth-gen adaptation of the early Bard's Tale series for old people computers, the game takes a refreshingly blasé stance on inventory management by automagically transforming vendor trash into money. The game will also automatically sell weaker weapons and equipment once found, and will replace stronger equipment with whatever is currently equipped and sell the old equipment, which of course wouldn't work in a more complex game. Ostensibly, this system was introduced to avoid bogging down the player with too much "game" to deal with, due to its status as a light-hearted pastiche of action RPG tropes, but all the same it's still a surprisingly effective system that cuts out a considerable amount of unnecessary busywork. Like the spiral text-input of Beyond Good & Light, it's a one-off feature that makes you wonder why it isn't more commonplace.
 
Torchlight - Torchlight's most interesting feature regarding item management is the ability to send one's pet into town to sell useless treasure. Doing so hardly interrupts the gameplay and is a huge time-saver. The game does become a little tougher without the pet's help however, so this trick isn't without its perils.
 
Fable 3 - An example of a novel system that doesn't work so well is Fable 3's pocket universe inventory, which more often than not adds unnecessary steps to checking one's inventory and makes it difficult to find many item types. Terranigma uses a similar pocket universe feature, though it can be navigated like a normal menu system in most cases.
 
Now for treasure variety. I've taken the liberty of ranking these from commonest to rarest (sort of like how the games themselves do it, which kind of make me wish you can change the font colors on Giant Bomb):
 
Gold - Obvious enough. Currency is needed to buy anything and is the most valuable commodity available in practically every game that uses it. Games will occasionally change the name to keep things interesting though. I hear the Gil -> Zenny exchange rate is ridiculoid right now.
Equipment - A necessary part of any RPG character's inventory is the stuff they're wearing to fight bad guys. Some RPGs will scale equipment drops to the character's level, or to the difficulty of the dungeon you're in, meaning any given piece of equipment you find is comparable to what you may already have equipped. Others will have you routinely stripping dead enemies for their mediocre armor (it didn't do them any favors anyway) for selling. What's more interesting is how the game decides how many pieces of armor a character can equip (occasionally getting ridiculous with leggings and arm bracers), and whether or not it still takes up storage space if it's being worn.
Consumables - Potions and the like. Though incredibly common in some games, where a player's health potion stash starts to number in the hundreds, they can also be very rare and valuable tools in others and players often need to save them for when absolutely necessary. I'll also include ammo here, since characters that use it consume it at quite a rate (though perhaps more commonly they simply fire them from their bows or guns).
Junk - These items have no other use than to be sold for cash. This seems slightly pointless; like getting pocket change while trick or treating to later buy candy with, adding an extra step to one's Halloween process. It does add to the variety of things you can find, though, and you can happily sell this stuff without worrying about it being useful further down the road. In most cases.
Crafting Ingredients - Occasionally indistinguishable from the sell-only stuff, the materials you can find while adventuring have their uses in the game's crafting system; turning useless scrap into something useful. Most of the time these items are parts of monsters that either fell off mid-battle or that the characters took their time to remove from the corpses with knives/pliers/ice cream scoops, though there's usually a lot of harvesting ores and plants and such too. MMO jaunts tend to get unfortunately weighed down with hunting for this shit.
Fish - If there's a fishing mini-game, it's likely that these piscine peeps will show up. I guess it depends on what, exactly, you're fishing for, but in most cases it's usually fish. Fish will either act as a crappier alternative to potions or will occasionally have unique benefits that apparently only aquatic life can offer. Like Omega-3, perhaps, or that thing that makes sharks immune to Alzheimer's that Deep Blue Sea was all about trying to find before people started getting ate. This is kind of a departure, so let's move on.
Collectible Playing Cards - Your guess is as good as mine with these. People like CCGs, I suppose, so it makes sense that monsters would go out of their way to craft cards in their own likeness and leave them to be picked up upon death as some sort of memorandum. Total sense. This also includes figurines or books. As long as they don't make the drop rate abysmal, it's actually a neat (if completely incomprehensible) way of getting to know the monsters and the wider world which they inhabit.
Glass Bottles - Why the hell are these so rare? Poor Link could've been farming fairies for the end of days (which for him is occasionally half a week away) if fate ever let him find more than four. Woe betide his enemies if he ever stumbles upon his local recycling facility. I suppose anything that can take down Ganondorf should be meted out sparingly.