The Golden Bough, by James Frazer. For some reason, I don't recall why, I had occasion to look up a movie called The Wicker Man; and somehow, I also don't recall how, that led me to this book which has been transferred in its entirety online. In any case, it was written a good ways back in the century, but if you wade through something of an antiquated style there's all sorts of interesting information about pagan ceremonies and beliefs.

Flow, by Jenova Chen. Scott found this one, it's...oddly relaxing; a wonderful piece of art, if you ask me.