As for Infinite Powers, the chapter on CT scans was a fantastic read. I wish there had been more modern applications and less of the book devoted to the run up to calculus, which spanned the majority.
I loved the whole run up. The CT story was great.
It's gotta be really hard to write a book about math.
17 equations that changed the world is another math book in a similar vein I would recommend.
I'll have to check that and the calculus book out - love books about mathematics. Another good one, and probably the grandfather of them all is 'One Two Three Infinity' by George Gamow. The story behind the creation of the square root of -1 alone makes the book worth reading.
Midnight at Chernobyl is awesome. The scope of the disaster and the remediation required over years was far beyond anything I'd expected.
Gotta come out of posting retirement for this one. Math's my area, and I'm thrilled to see discussion of math books pop up naturally.
Simon Singh is an author to look out for, doing great popular-level math writing. My favorite, bar none, is The Code Book. It gives the history of cryptography and cryptanalysis - he describes the advent of a new cryptosystem, the mathematical flaw that people found to exploit the system, then the next (more robust) system which removes that flaw, and the cycle repeats.
Paul Lockhart's book/essay A Mathematician's Lament is an absolute touchstone work which I have shamefully not gone through.
Gödel, Escher, Bach is another seminal work. Hofstadter weaves together a tale of the math of Gödel, the art of M.C. Escher, and the counterpoint of Bach, through the unifying theme of self-reference. This is by far the most challenging read of the three I've described. I've started it about 8 times (... that's a great sell, right? ...) and I'll finish it one of these years.
The Man Who Loved Only Numbers (by Hoffman) is a beguiling read about Paul Erdős, a Hungarian mathematician who was exceedingly eccentric (a savant?). He's one of the most prolific mathematicians ever, and kept well-fueled by amphetamines. When a friend bet him that he couldn't forgo his stimulants for a month, he did just that and then exclaimed that all his friend accomplished in the bet was to set math back a month.
Ian Stewart seems to be broadly popular, for reasons I can't quite understand. Maybe there's something there that piques your interest, though.