Naglfar

Naglfar, in Norse mythology, is described in the Prose Edda as a ship made entirely from the fingernails and toenails of the dead. During Ragnarök, Naglfar will be freed from the land and sailed to Vígríðr, the battlefield, by Hrym along with an army of jötunn (race of nature spirits with superhuman strength). The ship will lead hordes against the gods in the last war at the end of time, before a new world will arise from the sea

The ship's name may have originally meant "Wraith ferry," but Snorri Sturluson in the Prose Edda provides a folk etymology of "Nail ferry" (nagel, "nail"), urging that no dead be buried with uncut fingernails, lest any more material be added to it. This lore could not have assumed this form had it not been for a funeral custom of paring the nails of corpses and the desire to make this a pious duty. It has also been suggested that Snorri's "nail ferry" or "nail-farer" is an metonym for a ship which is constructed with nails.

From: http://en.wikipedia.org/wiki/Naglfar