• Download the WoW model viewer installer from here: http://code.google.com/p/wowmodelviewer/downloads/list
• Select "yes" when it ask you if you want to load World of Warcraft now.
• Choose your desired character's race on the left (once the model is loaded you can edit skin color, hair, etc. on the right)
• Select an Equipment slot on the right, i.e. Shoulders - you can now start going through every Shoulder model in the game and it will display the gear you have selected on your character in the Model Viewer.
• Write down the gear you like and you can look it up on wowhead.com (or another similar site) to see where it drops

Creddit