How about Them: Adventures with Extremists - a series of interviews with some of the world’s nuttiest weirdos (who often turn out to be quite charming).
I second these. “Consider the Lobster”, the eponymous essay in the collection, is available here, and I think it’s a pretty fascinating piece of short (well, not all that short) nonfiction.
I second The Tipping Point: How Little Things Can Make a Big Difference by Malcolm Gladwell ---- The “tipping point” is that magic moment when an idea, trend, or social behavior crosses a threshold, tips, and spreads like wildfire. The book is an exploration of how social epidemics work, whether they are fashion trends, diseases, or behavior patterns such as crime.
Also:
White Bears and Other Unwanted Thoughts: Suppression, Obsession, and Psychology of Mental Control by Daniel Wegner
Ooh, seconded. Wonderful book, which I’ve read many times.
How about:
Gödel, Escher, Bach: An Eternal Golden Braid by Douglas Hofstadter. One of the most eternally fascinating and confounding books I’ve ever tried to read. (Several times. I get half-way through, realise I need a short break, go and read something else for a while, and never go back to GEB. But – and here’s the important part – I keep on trying again. That’s how much I love this book.) And what other writer has ever managed (let alone tried) to create fugues and canons with words instead of music?
Seven Summits - A very underrated mountaineering book about the first 2 guys to attempt the now very famous “Seven Summits” challenge. One is very liberal and one is very conservative and many yuks ensue.
The Suspicions of Mr. Whicher - About a brutal Victorian murder. Explains the history of the detective profession and reads like a novel. Very well-written.
Pale Blue Dot - or really any Carl Sagan book. This one talks a lot about our solar system and then about aliens (including some speculation that we might’ve possibly already very briefly picked up some signals from some) and then about our species’ future in space. Absolutely fascinating.
Crashing Through - A 40-something blind man gets a chance at restored vision. It’s a small chance, and the vision would be very limited. Risks are as high as they can be, including loss of the minimal light perception he has, and cancer (a potential side effect of one of the drugs he must take.) He takes the chance.
Kon Tiki - Thor Heyerdahl sets off across the Pacific in a hand-made raft on a practical suicide mission just to prove it can be done. Shark-wrestling ensues.
Travels with Charley - John Steinbeck drives across the country with his poodle. Wins a Nobel Prize for it. 'Nuff said.
I’ll add my vote to anything Bill Bryson has ever written- it’s all excellent, IMHO.
Also, Antony Beevor has written three excellent military history books that I highly recommend for someone who wants a bit more detail than The History Channel provides but doesn’t want to be bogged down with technical minutiae or long lists of German Waffengruppe Commanders, either: Stalingrad, Berlin: The Downfall, 1945 and The Battle For Spain: The Spanish Civil War 1936-1939.
Thomas Pakenham’s The Scramble For Africa is excellent, too- certainly the best overviews of the European colonisation of Africa that I’ve read.
Also, Simon Winchester’s Outposts: Journeys To The Surviving Relics Of The British Empire is a great read, too.
Finally, I’m going to stretch the rules a wee bit and nominate all of George MacDonald Fraser’s Flashman books. Yes, technically they’re fiction, but they’re so impeccably researched and annotated (and even have a limited bibliography!) that I think you can regard pretty much anything in them not directly involving the protagonist (or his wife) to be historical fact- or near enough to it to make no real difference- and a heck of a lot more readable than many “serious” works on the same subjects, IMHO.
Bill Bryson! YES!
I have a list as long as my arm, but I just want to mention “Uncle John’s Bathroom Readers”. I must have 20 of them, somehow more come out every year! I give each of us in our family a different version every Christmas, and long after the sweaters are put aside, the ‘body butter’ sits on a shelf untouched, the wine guzzled and the mixed nuts eaten - there’s a fascinating compendium of useful and interesting articles suitable for reading in short bursts while waiting for something to happen…not just in the bathroom! 
They can save your sanity in many situations.
The Medical Detectives by Berton Rouche - a collection of articles by a journalist who wrote for the New Yorker from the 50s onwards, each chapter presents a bizarre medical mystery (a man with blue hands whose circulation was fine, a man to whom everything smelt bad, to the extent he could barely eat, a child with seeming intermittent poisoning who had not ingested any poisonous substance etc.) and the steps that medics went to in order to track down the reason.
We had two volumes when I was young, and I read them until they fell to bits.
Word Freak by Stefan Fatsis is entertaining sports journalism, with the author finding himself sucked into the world of competitive Scrabble playing.
If you like the Colin Turnbull, might also be worth trying his The Forest People. Other travel/ anthropology lite recommends include Redmond O’Hanlon (I think Into the Heart of Borneo is his funniest, and most accessible book) and Nigel Barley’s The Innocent Anthropologist and A Plague of Caterpillars, both books about his time spent doing fieldwork among the Dowayo in Cameroon.