Even when I collect enough items to craft a dragon (e.g. Arrowheads for the Amazon Dragon) I always have some stuff left, because I never manage to collect enough for a second dragon. So my storage is cluttered with things I have no use for.
Here's my idea: These left-over items could be used in the Spell Shop to craft Spell Scrolls or Nether Dust.
For example 20 left-over items of any kind = 1 Spell Scroll
What do you think?