A spirit box in voodoo contains the spirit of the dead. One can be seen on the Hunter's desk on the official site, seemingly connected to the Haitian deity Ogun due to the symbol on its lid and the text that goes along with it:
The box is empty. But when you stare into the emptiness... Fèrè Fèray tout ko Fèray sé kouto, Fèrè Fèray tout ko Fèray sé manchèt.
The last sentence, translated, is one of the songs to Ogun (Ogou Fèray in voodoo):
The body of Ogou Fèray is covered with knives,
The body of Fèray is covered with machetes.