This might not be a great practice especially since children scare easily but still there are quite a number of relevant stories which you can tell during a storytelling session in a Halloween party or event. Even if it's not Halloween, you will always have a request from your listeners to tell a scary story. So people have more excuse to demand a scary story during this day of the year when spirits and monsters are supposed to be free to roam the surface world.
Aside from scary stories, you can also narrate mystery type of stories. Having a storytelling session in your Halloween party program will keep the children quiet and at bay. This is also a good opportunity to prepare other things for the party.
What stories to tell? You can search the internet for various short scary stories that have both the Halloween scare factor and at the same time children will learn something productive and inspiring at the end of the story.
You can even draw from personal experiences or stories. It;s often cool hearing a story from someone who has experienced it first had or was really there. This gives the story a personal touch and the kids just love the idea of stories happening for real.
Remember not to overdo it though. These are children we;re talking about and if you scare them witless, they will certainly have nightmares and you'll have parents breathing down your neck the next day. Now that would be a real scary situation for you as organizer or storyteller.
If you lack some modern shorts and have not time to prepare your own stories, you can always turn to the classics. There are several classic ghost stories that children nowadays have yet to hear.
The Legend of Sleepy Hollow is one of them. The headless horseman of Washington Irving is sure make some children gasp. You can tell the story of the Flying Dutchman, a mysterious ship that is said to be a doom ship that brings bad things to other ships that crosses their paths. Dr. Frankenstein's monster is also always popular.
Another classic is A Ghost Story by Mark Twain which has several adaptations that you could read for the kid's enjoyment. Algernon Blackwood's The Willows is said to be the best ghost story in history. You might also find some suitable adaptation for children somewhere in your bookstore or on the internet. Another work of Blackwood is The Empty House which is also pretty good.
Now, I have to remind you at this point that you will be reading these stories to children. You might want to kind versions that would be easier for children to grasp and understand. If you're Halloween party is for adults, which I also think putting a storytelling session is a great idea, you can be as eloquent as you want. But in the meantime, simple and short adaptations would be better for children's party.
If for some reason you can't get any storytellers for your party, other options would be buying an audio or video CD of various ghost stories. There are several of these in the market and you can easily buy one off the rack of your favorite bookshop or audio store.
The idea here is to keep your options open. Of course Halloween parties involve game and prizes but having a Halloween storytelling session can be both fun and productive.