Eventually new schemes and blueprints will be added that use more and more of our items but until then there are a few items that only have one or two uses are are just piling up in our accounts.

Once these items do have more uses it will take a a while to get the economics for them back to a stable level just due to the huge numbers. Supply and demand; and right now the supply is so insane even once there is a demand for them it will take a long time to use up the excessive amounts of these things.

So I purpose, at some point before new buildings and items start rolling out that require them, to have some kind of event where users turn in these items for some benefit. A contest maybe, where the people who turn in the most get a reward of some description.
Maybe the mages need to collect ink because they need to rewrite the entire history of the universe. Maybe an epic monument, usable as a "daily" to the entire userbase, needs to be built out of granite and shells. I dunno.

The items I've noticed have the most surplus and smallest market are:
(And for fun, the amount I have in my inventory right now.)
Cuttlefish Ink - 1700
Granite - 680
Marble - 600
Ore - 530
Quartz - 570
Shell - 1500

And to a lesser extent:
Lazulite - 300
Magnetite - 180
Ruby - 160

TLDR; Before new buildings are released that use the junk items hold an event to remove as many junk items from the market as possible so they can have value again.

I support this. With cuttlefish and shell in particular, it's gotten to the point where I don't really feel the need to explore water tiles, since I have way more than I ever could possibly need.

I was considering suggesting other craftable items such as schemes and blueprints with the cuttlefish ink - perhaps with a requirement of a drafter's table and/or having the maximum number of schemes learned in order to know it by heart and draft a new schematic. So learning 5x of a stable 2 schematic, for instance, would allow you to be able to craft it.

Definite support. My inventory is clogged with cuttlefish ink.

Support. I'm fairly new here and I've already piled up a mass amount of those items. I think a contest would be great.

No support, if you have items you don't need you can sell or discard them, and if there is a contest type thing about turning them in it will end up being bias towards the older users who have had time to accumulate such resources.