I'm getting more into non-fiction these days.
I just finished 'The Calculus Story' which, funnily enough, is a story about calculus. A pretty quick read but fairly in depth although not in depth enough to actually really learn much calculus from. I happen to be studying calculus at the moment at the OU so a good bit of extra reading, more for the background of the subject.
I'm now getting into 'Mathematics for the Non Mathematician' which also pretty much does what it says in the tin. These maths cunts don't fuck about with their titles.