Hmm.
Oh! Looking at Grinity's post on Bill Bryson reminds me of "A Short History on (or was it of?) Nearly Everything". It's about exactly what the title says, from quarks to evolution to electricity. Great book on science.
"Into Thin Air" is a great book about a tragedy on Mount Everest. It's pretty long and should fulfill almost half of his 1000 reading requirement.
If he can stomach it, "Deadly Feasts" is one of my favorites, about BSE (mad cow disease), how it was discovered, similarities to other diseases, etc.
"Planet Chicken: the shameful story of the bird on your plate" is about how chickens are mistreated as they are raised for their meat and eggs. Also a somewhat gruesome book, and I found this wonderful book in Britain, so you might have trouble getting it if you're in the U.S.
"Longitude" is short but great. It's about the quest to make a clock that can still keep accurate time at sea to help measure longitude. A reward was put up for such a clock in Britain, and John Harrison attempts to make the clock. This book was one of the first nonfiction books I ever read. It was a great introduction to the genre.
I do remember there being a book on the history of salt I enjoyed, but can't recall the exact title.
"Communism" by Richard Pipes is what I'm currently reading right now, it's a brief book on the history of Marxism/social democracy/communism, but the first chapter may be a little advanced and boring for DS13 unless he really enjoys reading about governments and economics.
"Cool It" by Bjorn Lomborg (sp.?) is a very interesting book about global warming and presents a unique point of view that is often lacking in books on the subject. (I may be biased here, as I'm a skeptic.) :P
That's all I can think of for now. I hope this list will help your son.
