This is not my addon. The orginal is by Filiassin and a subsequent update was put out by Ggman. I have just updated the item database with all the ICC loot heroic and non-heroic.
Function: Adds data at the bottom of item tooltips detailing where they come from.
Original Addon(You do not need to download these for the mod to work. All data from these versions is included in the download.):
WoWInterface Plagueworks Update