I have a couple books on garnishing nothing specific to carving alone. "Great Garnishes" by Huang Su-Huei has some nice carving in it. He uses more veg.'s to carve than fruit but he has some elaborate watermelon carvings and other interesting fruit work. For non traditional garnishing I enjoy the book "Play with your Food" by Joost Elffers, I think it's rather fun.
I really enjoy doing this kind of work, it's rather fun too.