In 2003, hiker Aron Ralston amputated his own arm with a pocket knife after a boulder fell and pinned him down.<p><a href="http://hike.mountainzone.com/2003/news/html/030502_amputate-arm.html" rel="nofollow">http://hike.mountainzone.com/2003/news/html/030502_amputate-...</a>