Headless Horseman:

Should the headless horseman come back, I know I have heard a lot of people say they want to catch his steed. I think it would be great if he dropped some wearable avatar item little colts of his steed. ;)

Crafting System:

#1: If the crafting system is up by then, I think it'd be fun if we could collect paper off of pranked trees and craft them into mummy-wear items, a held item paper ghost, paper lantern, a paper lanterns background, etc.

#2: Since the site already has apple trees and collectable apples for the Orchid, some sort of crafting element akin to bobbing for apples -> apple pie making; pumpkin carving -> pumpkin pie making = Turn in pies for some sort of reward might be an interesting idea.

Shop Items:

I think some of the shop items from this year having some extra colors next year could really breathe some extra life into the items, such as the held animals (ghost cats, dogs), and the moon backgrounds.

Or dropped "Demonic Steed" eggs! Have a chance when you beat the horseman and his horse you can find an egg that will hatch into a little demonic steed of your own. ^^