I've had great sucess using the By Realm... tab located under Quests, it lists all the quests for whichever realm you choose in alphabetical order, and tells you the level your toon has to be to start/get credit for the quest, you can also search for specific slot items and see where they came from, for example you need a jewel slot item, so look up equipment by realm and slot, then when you see a jewel you like, look to see where it came from, like if it's a one time drop or a quest reward or just a random drop, etc etc. The name of the quest will be there under related quests, and you can click on it to get a full description/ walk though of the quest just like using the realm tab mentioned above.