Death in Yellowstone
Great book. Picked it up and had trouble putting it back down. Highly recommended read. I just wish it was more updated, as it was printed in 1995 and I know of two deaths since then (one in the last month since I've been there). Fascinating stories about people, some of them candidates for Darwin Awards.
Many are morbid. Good read for those fascinated by death, and for anybody who might think walking up to a bison to pet it sounds like a good idea.
Along the same lines, I think this would also be an interesting read.