My normal game runs on Saturdays, so we're definitely gaming that day.
I often run Halloween themed adventures for this season.
My most successful ones have revolved around taking classing monster or horror movies and turning them on their heads.
For example, consider the idea of a community where it's suspected there are Werewolves. People have been found, killed, their throats ripped out and their bodies torn by animals.
A local nobleman offers a reward for the head of the Werewolf (proof required), and organizes the villagers to go out on the nights of the full moon to try and catch the monster.
The nobleman, by the way, is a Vampire, and he's behind the whole thing. No Werewolves, just him and some of his vampiric abilities. Remember that, aside from turning to a bat or mist, a Vampire can become a wolf or dire wold as a standard action, and can use the "Children of the Night" ability to call for a pack of wolves once per day. These less commonly used abilities make a perfect cover for a story like this one.