Old roof slates, brilliant things! They come pre-drilled, sometimes pre-broken into interesting and attractive shapes and you can write on them a la a Victorian schoolchild.
For some reason we have stacks of these (probably the same reason we have boxes of rusty metal and shoe lasts – AKA Interesting Things) so I grabbed the most attractive one, brushed off the dead spiders, knotted twine through the holes and hung it on a handy nail. Now I can write messages to myself in a more attractive way than using, say, a whiteboard *shudder*.
P.s. I have nothing against whiteboards per se. I know there are probably thousands of attractive, useful, well made whiteboards in the world, but I’m a teacher. Enough said.