I tend to read relatively little non-fiction (that is outside work and purely for pleasure).
It tends to be either photography (mostly to look at the pretty pictures
), or popular science. Currently I'm currently reading
The Sexual Paradox by Susan Pinker and not that long ago
Freakonomics. There are a range that I dip into from time to time, e.g.
What's Your Dangerous Idea.
I guess most non-fiction I read is not books: newspapers and magazines (e.g. New Scientist).