Got a few ideas for improving the current stockpile system. Quite a few of these are also suggested before, but placed here to consolidate.
1. Re-designate Stockpile
Give stockpile a similar ability to a room to "resize" it. So when used, the player can move a custom stockpile around, expand, or shrink it without having to go into the custom settings to set them up again. The old stockpile will be deleted when it's redesignated.
2. Multiple Stockpile "take" destination
Suggested before, and not sure why the limitation is there, but a stock pile that can only have one other stockpile taking from it, this makes food/alcohol distribution in a fortress more difficult since one essentially have to daisy chain the stockpiles, creating un-necessary hauling. Of course, having this ability lead to...
3. Maintain stock
Important for food, alcohol, and ammos. This may require an interface change to allow maintaining a certain number of stock in a stockpile by taking from its source pile (the stockpile to take from). It can be something like the number of allowed barrel setting, except in this case the stockpile tries to fill up a certain number squares in it.
4. Workshop Input/Output Stock
Ability for a workshop to designate one or more stockpile as its input. And either as a global order or workshop specific orders, require the workshop to use available raw material from the stockpile first (except when the dwarf is in mood). This will allow a better control of item creation and more efficiency. Having output stockpile that is an input stockpile for another workshop will further improve it. It will be a plus, but probably not by much.
5. "Carting" Stockpile
This could be a partial solution to post battle hauling. Allow a stockpile to generate a sort of temporary extension out onto the battlefield. If deemed closer, the dwarf will haul the items onto said stockpile, and once full (or ordered), a dwarf will bulk carry the item on the stockpile back to the original stockpile.
6. "Pitting" Stockpile
This could either be a pit designation with stockpile interface or a stockpile with a "pit all on stockpile" option. Allow you to auto-pit specific items (goblin narrow clothes? down the magma it goes). Of course, a system to prevent quantum pitting should be in place to prevent abuse.
7. "One-way" Stockpile
Good for the legendary artifact and what not, a stockpile that auto-designate anything place in it as forbidden, until you un-forbid it (the designation is only given when it is placed on the stockpile).
8. "Immigration" Stockpile
Maybe works better as a zone, but an area to "store" immigrating dwarf and give you time before you "integrate" them into your society. This is from a desire to create a genuine form of an "airlock" system to ensure the inner fortress never have a path to the outside world (all build job outside is completed by drafting a crap-load expendable dwarf, get them to haul building materials/food/alcohol to the airlock, cycle it, and commence building).
And that's what I have so far.