The Acorn Wand

This is just cool.

Puzzle hunts are a popular pastime at Microsoft. For the Microsoft Intern Puzzleday 2007, the puzzle design team decided upon a Harry Potter theme. Competitors ("students") formed teams ("study groups") as they attended classes at the Hogwarts campus at Microsoft. Of course, since this is Harry Potter, you need a magic wand, so the puzzle design team made a bunch of functional magic wands.

Wand web site here.

Clarke's Third Law in action.