Objectives
You must search the world for a being capable of restoring the power to the Fragment of the Dragon's Eye. The only information you possess about such a being is that they exist.
Provided: 
Fragment of the Dragon's Eye
Description
A fragment of the shattered medallion is all that I can offer.
You must find another of dragon blood willing to assist you in forging a new key. Once you secure this key, you must travel to the Wyrmbog in Dustwallow Marsh. It is there that you will find her lair, adventurer.
Where to find other flights willing to help? Sadly, I do not know... They are said to exist. Some may even work and live among us, disguised as one of the humanoid races. I wish you luck.
Progress
I sense an aura of evil radiating from you, friend. What could you hold that emits such an aura?
Completion
I should have known - a piece of the black dragon brood mother, Onyxia. How revolting...