In the 5th century BC, in Celtic Ireland, summer officially ended on October 31. The holiday was called Samhain , the Celtic New year. On that day, the disembodied spirits of all those who had died throughout the preceding year would come back in search of living bodies to possess for the next year. It was believed to be their only hope for the afterlife. The Celts believed all laws of space and time were suspended during this time, allowing the spirit world to intermingle with the living. Naturally, the living did not want to be possessed, so on the night of October 31, the villagers would extinguish the fires in their homes, to make them cold and undesirable. They would then dress up in and parade around the neighborhood, being as destructive as possible in order to frighten away spirits looking for bodies to possess.
Around the eighth century, the Christian church made November 1 All Saints' Day to honor all of the saints that didn't have a special day of their own. The mass held on All Saints' Day was called All Hallowmas (the mass of all Hallows -- saintly people). The night before was known as All Hallows Eve. Eventually this name became Halloween.
 Jack O' Lantern
An Irish legend tells of Jack, a lazy but shrewd farmer who used a cross to trick the Devil, then refused to free him unless he agreed to never let Jack into Hell. The Devil agreed. When Jack died, the Devil wouldn't let him into Hell. So, Jack carved out one of his turnips, put a candle inside it, and began endlessly wandering the Earth for a resting place. He was known as "Jack of the Lantern", or Jack-o'-Lantern.
See the Howto here
Some more spooky pumpkins
Mo. 31.10.2005 Party: Halloween DJ Kai B. DJ K.Simon DJ CEWA -Freibier (außer Cocktails) -Cocktailbar -Knüppelkeller Einlass: 21:30 Eintritt: VVK 12,--€ / AK 15,--€