I got a little creative with the figures:
The rook was turned into a ghost executioner with an executioner's mask in a tower ruin.
The knight, also known as the horse (at least in German), was turned into a ghost cowboy with a cowboy hat and a plush horse in his arm.
The bishop was turned into a ghost jester with his jester's cap - the idea was borrowed from the French.
The king and queen were outfitted with crowns and corresponding robes.
The pawns are an army of smaller, cute ghosts.