Hey, I just had a brainstorm for the spinner, dunno if you guys will like it or not, but since we're using cogs, what if we combine the spinner with the cogs, so the end of the dungeon items have functionality? The spinner and cogs go hand in hand in regards to shape,so they could work great in tandem.
There are some levels that we could give here, like, if you have the Kokori cog, you could use it on green or wooden or whatever switches, and open certain paths that way, once you have the Goron cog, you could open either red or metal or stone switches. This essentially makes it like the beams in metroid prime, that you would need a certain beam/cog to open certain doors, blocking progress without having advanced the plot.
Or, the cogs could give the spinner certain abilities depending on which cog you equipped. If you equip the Kokori cog, you could do a tornado, if you equip the Goron cog, you could either shoot fire or maybe interact with certain machines or stone. The Zola cog could make it rain or let you surf across water, or perhaps just a water attack.
Anyway, that was just an idea that occurred to me. I like giving end of the dungeon items functionality.
Also, as far as items, I'll actually go ahead and fill out some of those formats that MG suggested a while ago.
edit: I'll try to put these in the order I guess you'd get them/a logical order at least...
Proposed Spinner and Cogs
Spinner
Found in Hyrule Town
Press the button to board the spinner. You can zip around on it For a short period of time until your momentum runs out, allowing you to use it to make quick dashes to get away for things, but not to use it as a horse. It also works as a gear/cog to open some doors that had a particular indent in the floor, the same as twilight princess.
No requirements for use
Forest Cog
Found at the end of the Forest Dungeon
Equip it to the spinner to gain the ability to start small tornados. When equipped, hold down the spinner button to charge a tornado, and release it to release your twister. Tornados spin around the spinner, rather than going off on their own, because that doesn't really make sense...
Tornados can blow enemies away, like the gale seeds, or perhaps stuns them, but works around the radius of the spinner. Some puzzles activated by wind can be solved with these tornados, such as ones involving windmills getting started. Also, in certain places creating a tornado can spin you up to a higher level, like in TMC Wind Tribe Area.
Also, having this spinner equipped makes the spinner a little bit faster, in general.
Creating tornados uses a little magic?
Earth Cog
Found at the end of the Goron dungeon.
Equipping the Goron cog to the spinner and holding down the button charges a small earthquake. This stuns enemies in a larger radius around the spinner, and can kill some small ones. In certain situations, charging the spinning Goron cog causes some stones to rise or sink into the earth to create pathways, or sometimes causes metal to bend and create bridges.
Also, the spinner goes a little slower when this cog is equipped.
Creating earthquakes uses a little magic.
Ocean Cog
Found at the end of the water dungeon.
Equipping the Zora cog allows the spinner to charge up a water-based attack that can put out torches and fire enemies, as well as doing damage. The spinner with this cog equipped can also ride along special currents in the ocean and in rivers that flow too fast to swim. You can travel quickly and reach some inaccessible areas this way.
Also, when the water cog is equipped, the spinner can dash for a little longer before it runs out of momentum.
Shadow Cog
Obtained at the end of the sheikah dungeon.
Equipping the spinner with this cog and charging it would distort any nearby illusions and allow you to see through them, like bottom of the well type walls, or invisible platforms. Releasing a charged spin with the Cog of Truth would dispel any illusions and make the unseen visible for a short amount of time. It would also do some damage to enemies. And have a really cool animation.
The Sheikah cog either boosts your magic power while you're using it, or else makes it so when you use the spinner to dash quickly, you do a little deku nut teleport thing. The latter might not be a good idea...
Besides these functions, when each cog is equipped, you'd be able to open corresponding spinning locks. The forest cog could unlock wooden locks, the Goron one could do stone the Zora one could do... Water... Type locks. And the sheikah one would undo... Black colored locks. Those last two types of locks are sketchy, though.
Furthermore, it'd be cool if each cog ability was necessary in the final boss fight. You'd have one stage where you'd need to stun gannon with tornados, then you'd need to manipulate rocks he tries to use, then you'd have to put out flames he shoots, etc.
Also, I don't know if this counts as an item, but it's been mentioned that Link should learn thief skills from Ganon, one of them being tightrope walking. I did the same thing in my game as well, but I think this skill could be used to get into the first dungeon.
Functionality: when walking along a rope or other narrow space, you walk automatically in the direction, but must use the other directional arrows to keep your balance, like grinding in Tony Hawk. There could be a leaning meter, and if you lean too far, you fall.
Slingshot
Found in the deku forest, needed to access the forest dungeon.
Fires a deku seed when you press the button. Perhaps we could implement ember seeds and ice seeds like fire and ice arrows, especially if the bow upgrade is optional, but burning and freezing puzzles are not.
Must have deku seeds to use.
The slingshot can be used to hit enemies from afar, and is the most basic ranged weapon. It does minor damage to enemies. The projectiles can also be used to hit basic impact switches that are out of reach, eyeball switches, and when necessary, knock some hanging items down.
Bow and Arrows
Upgrade to Slingshot
Optional upgrade, found through side quest? Or else mandatory upgrade that is made necessary mainly through the increased range, or else the bow can trip switches the slingshot couldn't.
Functionality is the same as the slingshot, except it shoots arrows instead of deku seeds, and can facilitate the use of multiple types of arrows, fire, ice, etc
The main use of the bow would be making the slingshot a more powerful weapon, perhaps with more range or better aiming, and allowing fire and ice arrows to be used. Fire arrows could burn things, to light torches and open pathways blocked with wood. Ice arrows could freeze things to use as stepping stones, or freezing some things would make them breakable, for instance freezing a certain type of plant would make it so you could shatter it and get past.
Goron Drill
Found somewhere on the mountains, used to get onto the Goron mines.
The Goron drill would be a new face to the mole mitts, but function essentially the same. We could have a rapid tapping thing necessary, like how the spinner was spun in TP. This could drill through some walls that bombs couldn't do. However, bombs could take care of walls this couldn't handle. However, this seems a little redundant, maybe one or the other? The only way I can think to make this not gimmicky is if the drill came much later in the game, and could go through walls http at needed to be bombed as well as harder walls, and it could drill tunnels like the mole mitts, so you wouldn't have to lay bomb after bomb. Like how the megaton hammer kinds replaced bombs in OoT, but you still needed bombs for their timed and ranged capacity.
Bombs
Found in the goron area. Maybe found to get into the mines, instead if the drill, which seemed a little gimmicky. These could blow up any walls that needed to be destroyed, function the same as in other games.
Hookshot
Found in the forest temple, used first to traverse the forest canopy, going from tree to tree and branch to branch.
When you press the button, the shooting end extends on a chain from the grip. When the hook end hits your target, it stuns enemies and removes whatever power ups they might have, destroys some things like pots, latches and pulls in light objects, and drags link toward larger anchored objects it can attach to. The hookshot can drag you across gaps, activate switches if they're close enough and the right type, as well as be useful in combat.
A hookshot is used by one man in a port town as a tool to pull ships in to the docks, but was discontinued because it just kept pulling him into the sides of boats.
One last item that I would always like
Logbook
Found somewhere in Hyrule town
Equipment, accessible from the item screen. It keeps track of where things you've seen are. For instance, when you're playing and you're like, oh, I know I've seen one of those puzzles where you need magic beams to solve it! Uh, where was that? The logbook would have categories, such as spinner, slingshot, lightning rod or whatever, and looking in that category would display the map with the general location of puzzles you've already found, but haven't yet solves. Once you solved them, they'd have a little complete symbol.