InspectEquip also supports the popular Examiner addon and is translated into a variety of languages.
InspectEquip can also add detailed item source information to every item tooltip, including boss information or Emblem cost. Here, the last two lines are added by InspectEquip.
This is the panel you'll see when inspecting another player with the default interface. In this image, the option to show the item levels of all items is enabled.