The memo board was originally devised to use in the shower and it was almost called a shower board. The fact that it is waterproof means that it is easily possible to use in a bathroom and the writing will not wear off and the pencil still works when wet.
Some people do get great ideas when in the bath or shower as they relax. You could write them on the tiles with a chinagraph pencil, but it is probably much better to write them on one of our boards as you can move it out of the shower, to transfer the ideas on to paper or even photocopy them.
You may even find it useful for recording your weights on as most people keep scales in their bathroom, as well as ideas, lists and things like that.
The transparent board can easily be hidden in a bathroom if required or a florescent one can stand out easily.