"The Blizzard be strong outside, lads; settle yehself in and breathe the steam; we'll pass the time with a story."
An ancient shrine of a mischievous goddess. The proper offering will give you her blessing, but 'ware you don't feed her wrong!
In one region of a forest, all of the trees are identical, down to the leaves and the twigs. If the PCs carve something into one of the trees, it could mystically propigate until it covered all of the trees, or could vanish since it was not carved into the one true tree.