Delight all of your guests with a big cauldron of Epicurious' non-alcoholic Witches' Brew - just add rum if you like spiked punch.
For the greatest effect, splurge for a classic, black cauldron (we love this large, plastic one from Amazon.com).
Cool the drink using large quantities of dry ice so that each cup will be brimming with "mist." (NOTE: Dry Ice can be dangerous and cause injury, so be sure to take precautions)
And what's Halloween without a little blood? Set out a large pitcher of Epicurious' Bloody Marys, a row of high-ball glasses (or medium-sized plastic cups if you don't have these handy) and a small plate of celery sticks to garnish and let your guests help themselves to this great drink.