The American tradition of "trick-or-treating" probably dates back to the early All Souls' Day parades in England. During the festivities, poor citizens would beg for food and families would give them pastries called "soul cakes" in return for their promise to pray for the family's dead relatives.
I am thinking of starting a free banner exchange for anyone with a paranormal website. If you think this is a good idea then let me know. If there is enough interest I'd start it up.