Simple World of Warcraft addon that allows you to easily check if you have completed a certain quest.
/qc xxxxxx (To check if you have completed the quest with code xxxxxx)
/qc [Quest Link] (To check if you have completed the linked quest)
/qc (To see this help)
If you dont know the quest code, you can obtain it using the wowhead link. Te code is the number at the end of the URL