Grandin Road has this excellent (animated!) Haunted Typewriter in their selection of decorations this year.
From the site:
Don’t just decorate, put on a spine-tingling show to write home about with our Animated Haunted Typewriter. The hit of your Halloween spectacle, they’ll still be talking about next year. As the unsuspecting approach, it simply appears as a forgotten writer’s relic.
Once the motion sensor is activated, the ghost at the keyboard repeatedly depresses the keys that spell, “H-E-L-P.” Paper carriage moves side-to-side, as typewriter sound effects play, adding to the spellbinding illusion.
SheWalksSoftly 