Helen Nodding's website features some fascinating art, but also the recipe and directions for making your very own 'moss graffiti'. I think it would be an awesome gardening/science/art project to do with young-ish kids, and they could easily be charged with the daily water misting that the new moss requires. I, personally, would love to do a swirling design from under the single tree in our yard...
Thanks to Helen, here's the recipe:
*Several clumps of moss
*1 pot of natural yoghurt or 12oz buttermilk (experiment to see which works best)
*1/2 teaspoon of sugar
*Plastic pot (with a lid)
After you've assembled these ingredients, visit Instructables for the thorough instructions.
I can't wait to make my very own moss smoothie!