Mathematics - Super excited to see the release last year of "The Princeton Companion to Applied Mathematics (2015) edited by Nicholas Higham (the numerical analyst).  This second, 1000 page collection follows the outstanding example of the "Princeton Companion to Mathematics" (2008) edited by Fields Medalist Timothy Gowers, which is one of the best surveys of current (last 50 years) of mathematics at the graduate / research level.  Nick's collection promises to be an absorbing read!

For the Princeton University Press announcement, with downloadable table of contents, preface, etc.
http://press.princeton.edu/titles/10592.html

For the original recommendation, see the thread here:
Surveys of Current (last 50 years) Mathematics at Graduate / Research level?  
http://math.stackexchange.com/q/657183/34365