So many. A couple of the ones I'm most anxious to dig into:
Tesla: A Portrait with Masks (Vladimir Pistalo)
Guns, Germs, and Steel (Jared Diamond)
West of the Revolution (Claudio Saunt)
The Enemy at the Gate (Andrew Wheatcroft)
How We Got to Know (Steven Johnson)
And, two of the stranger ones:
Oxford Atlas of the World (21st Edition)
The Natural History of Unicorns (Chris Lavers)
I think that my atlas is so awesome. It seems like it tells me everything I could ever want to know about geography, weather, tides, or currents, plus it gives a little information on topics as diverse as economy, culture, and astronomy. My schoolwide Geography Bee finals are coming up soon, too, and I'm going to try to become a back-to-back champion, so there's a practical element to it, as well.
I feel I've got to explain my choice on my last book, lest I seem crazy. The unicorn book traces the history of unicorns - where the legend likely began, what serious people regarded them as real back in the day (not too long ago, actually, I think), what they believed about the unicorn, their presence in various cultures, etc.; it doesn't actually say that unicorns are real or anything like that. I started it a year or two ago, but I couldn't really get into it. I'll try again soon. Some books are like that; you just have to give it a little bit of time, and then they become interesting.
As you can see, I'm more of a nonfiction kind of guy; however, I'm reading The Count of Monte Cristo right now, and though it's an abridged version, I'm really liking it.