My advice is to splurge and get a magnetic whiteboard. I recently bought a huge one at office max for around $150.

Having a giant "magnet board" is quite wonderful. You can hang papers, play with magnet "things", and even purchase magnetic whiteboard pens and erasures that magically stick to the surface - so you never lose them.

Back in my college days when I was broke, I did use these exact shower boards a few times. As mentioned by the author, they tend to not erase well and you end up resorting to using nasty cleaner chemicals.