Are they hollow and light? You could build a Flying Crank ghost with one. That would be cool to paint it white then RIT whitener the face. I'll bet it would look very realistic, more so than styrofoam heads.
for the last few years I have been hanging my heads in chains in my torture chamber and one with my guillotine. This year Iam thinking of having a graveyard with the heads face-up in fron t of the tombstones. I think it should be pretty creepy. I have also just used them under masks on my dummies, It has a creepy factor when you can see the maniquin eyes under the masks.