[Woodmonkey]

Tradition and religious beliefs, scotto.

The ferryman Charon carries the souls of the dead across the River Styx to the Underworld in his black boat. His fee for portage was either one obol, which was placed in the corpse's mouth, or coins placed on the eyes of the dead. Those who had not been given burial rites could not enter Charon's boat until they had wandered over the earth for 100 years.

http://www.vroma.org/~araia/charon.html

For anyone who thinks coins aren’t particularly spooky, consider this: It is a custom in some cultures to place coins on the eyelids of the dead to keep their eyes closed. Some believe that, if the eyes of the dead remain open, we would see our own death captured in their eyes.

Ancient Greeks believed coins are to be placed on the eyes of the dead as payment to Charon, the boatman on the river Styx, for ferrying the dead to the other side. For this service, he was paid a fee that was placed in the mouth of the deceased.

http://www.article-emporium.com/family-752.htm