I recently acquired (thanks to an amazing friend) a sketchbook that has what appears to be a parchment-like paper in it. Both she (my friend) and I bind our own sketchbooks, and this one wasn't doing a thing for her- so she gave it to me.
And I haven't let it go since. I started with sketches of "Amay-rum", and no doubt will do plenty more of other beasties and creatures and the like. :)