There is a "Gummy Bears" deck still floating around Amazon. There is even a Halloween themed deck by Kipling West. Themed decks and parody decks are so common lately that a classic Rider-Waite (Smith) feels hard to find.
Decorations and activities. Wow. I mean, I buy my housewares during this time of year so it's kind of "common knowledge" stuff to me. On the other hand, I almost never entertain at home.
Steve Jackson Games makes some quick and fast dice games: Zombie Dice, Halloween Dice and Cthulhu Dice. They're meant for smaller groups, but it seemed worth mentioning.
Jo-Ann Fabric seems to put their Halloween decorations on the floor at 50% off the stamped price. Most of it is old lady and soccer mom crafts, but you can find good things there too.
Music: My brother DJs on college radio stations, and insists on doing Halloween shows whenever the school lets him. He plays entire not-standard stuff and people will continue to thank him for it months later. You're on a good path by saying "nothing too cheesy."
I would only suggest this part for background music during planned activities. A group called
Midnight Syndicate is great for making Halloween background music, and they're a staple of those temporary Halloween stores that pop up every year. Avoid the album "Gates of Delirium" in favor of one of their themed albums.
Nox Arcana shows up too, but tend to be more ambient and low-key. You may also want to find the score to any horror movie you enjoy. Just make sure it's the orchestrated score and not the soundtrack. That music was composed to establish a creepy/scary/foreboding sensation.
Once it's time for open socialization you need to ask, "what do
your guests like?" If you can offer styles/genres that you would play at a birthday party then maybe we can help meet them halfway there. I could launch into all kinds of off-the-beaten-path Halloween themed music, but it's no good if every girl there wrinkles her nose and curls into a ball. I'm speaking from experience.