There are lots of pictures of stones in the Presentation Zen book by Garr Reynolds. I was early for a client meeting and spent a few minutes hanging around in a bookshop when I saw the book on display.
It was a 'must have'...
The PZ book is a gem for anyone interested in visual aesthetics. Beginning with Garr's familiar 'really bad powerpoint,' the book considers not only the design process for great, minimalist presentations but also how to combine images and words to maximum effect.
The foreward by Guy Kawasaki is a masterpiece. He says:
What we want to see: