Maybe there is such a mod out allready but i havent found it yet in that case.
Anyway, after questing an entire zone your allways left with a bunch of questitems that has no purpose once the quest is completed.
What i need is something to tell me what items i can destroy.
I don't know any names off the top of my head, but I know there's at least one addon (non-Ace, I think) that shows you the name of the quest an item is associated with in the item's tooltip. I used it a long time ago, but found that I didn't really need it. I believe it also colored the quest based on whether it was incomplete or complete, or no longer in your quest log.
I think there are also several general quest addons that include this feature, both Ace and non, but I couldn't tell you which ones...