eTravelerGear is selling an erasable shower tablet. "Record all your big shower-induced thoughts on our reuseable note tablet. Waterproof crayons (included) capture the flow of your creative ideas, to-do lists, and more for easy transport to and from the bathroom. Complete with crayon caddy and suction cup mounts."
Finally, something to prevent all my shower ideas from flowing down the drain. What an age we live in!