I've recently finished reading "British Town Class Cruisers: Design, Development, & Performance" and "Going Deep: John Philip Holland and the Invention of the Attack Submarine." You can read my reviews here:
Going Deep
British Town Class Cruisers
I've also just started reading the revised edition of "Scooter! The Douglas A-4 Skyhawk Story." Lots of pretty pictures, but I haven't had much of an opportunity to dig in too deeply.