In addition to last year's Halloween ideas for Latin classes, here are a few more...
You might consider exploring the Latin of Harry Potter. Ginny Lindzey shows the Classical connection in Just Charming: Tapping into the Latin Magic of Harry Potter.
Michael Myer, Magister Lingua Latinae at Heathwood Hall Episcopal School, has some fun materials to share with you on his class website, including a list of the parts of the body (Partes Corporis) that can be used for playing Simon (or Caesar) Says, plus the lyrics to Illa Ossa (sung to the tune of 'Dem Bones').
For those of you who use Professor John Traupman's Latin Is Fun, Book 1 as a textbook or supplement, there is a scary Monstrum in Chapter 12 as well as a wonderful skit about the legendary Roman scientist Dr. Franciscus Frankenpetrus.
Dr. Melissa Schons Bishop has organized a Halloween activity kit which can be purchased at her new store, Creative Classical Curriculum. With up to three days of material for each class, "Horrible Haunted Halloween Horror" includes readings and activities for all four levels of Latin based upon authentic Latin texts: a haunted house story by Pliny for Latin I, the werewolf story from Petronius for Latin II, Lycaeon's metamorphosis into a wolf from Ovid for Latin III and Aeneas descent into the Underworld from the Aeneid for Latin IV. Each selection is accompanied by magic vocabulary lists and active learning followups. Dr. Bishop also includes two complete games Monster Bingus and the Underworld Game. The kit may be downloaded for $40 -- keep in mind that it can printed out and used for years. Also available and suitable for Halloween is "Gross Roman Facts."