It's unusual music week on the blog, so put a theremin in your pocket! Modeled after the infamous instrument that lent spooky sounds to countless classic sci-fi and horror films, Thereminator ($2.99, available here) allows you to evoke the theremin magic by using the touch interface on your iPhone: simply move your finger horizontally to change pitch, and vertically to control the volume. Get creative with your touches to achieve unusual or even bizarre effects.