The other one was so popular, that we decided to make a number 2!
We need ideas for #3, so please post your ideas in a comment.
Thanks!
What do you do with emeralds?
Keep it all in a chest incase I might need it some time. Bonemeal is useful, as are arrows.
Gun powder is the best item in the game…apart from what you use it for. 
Same as liam.
It all just goes into a chest and is never seen again.
The only loot I actually use is potion stuff, but I do use arrows and bones.
With a grinder, most loot becomes pointless, so it goes in a chest until I sell it or I have a plan for it involving some huge project and a lot of time. If only you got bone blocks or skulls or something.
I discard of everything except Bonemeal and Rare items like heads.
Save everything! Well, actually just a double chest of each material at most.
Guys I must confess… I am a minecraft hoarder.
I used to have a lot of crap in my chest but I threw it in lava.