Dirk, you should check out "Eiger Dreams" and definitely "Into Thin Air" if you really
liked those Devil's Thumb chapters--it's what got me reading the rest of his books.
"Under the Banner of Heaven", of course, is totally different subject manner, but I
loved his style so much that I was curious to read it. Quite interesting.
Also, if you see the film and like it, you might like "Touching the Void":
http://www.imdb.com/title/tt0379557/