Finally, a new use for mathematics in the bedroom! (Modesty forbids talking of the older uses :)). Steven Strogratz in Group Think in the on-line Opinionator for the New York Times explains how Group Theory can be applied to the task of flipping a mattress. Why would you do it? For even wear, of course, and hence better sleep. You can flip horizontally or vertically, or rotate about an axis. These can be further sequenced into a plethora of choices. That is the where the splendid illustrations come in.
They make logical why you should simply "spin in the spring and flip in the fall". Worth a read. Steven Strogratz, who teaches at Cornell, is fast becoming the successor to the venerable Martin Gardner who wrote the Mathematical Games column in Scientific American for many years. Making mathematics enjoyably and relevant to those not trained in it -- now that's a noble cause.