"The Smashing Book 4: New Perspectives on Web Design", ISBN 978-3944540573
The lines in front-end development are getting blurry. Designers are doing prototypes using HTML5 libraries (like Bootstrap or Foundation) without going through developers. Developers are playing with animations and user experience design via CSS transitions and widgets like my own color-pusher. One needs a book where all the different tools aimed at designers and developers alike are collected. SmashingMagazine publishes tutorials, blog posts, newsletters and books that fit this goal.
On the other hand, my second favorite was "The Design of People" by Nishant Kothary. He shows how to start the project right, anchoring expectations and setting the project boundaries among stake holders. The approach is similar to Dale Carnegie's "How to Win Friends & Influence People" adapted for front end development ;)
This book is a great read, and could be read in any order. If you have a choice between an ebook and printed version, get the printed one. It is an example of beautiful EU polygraphy, hardcover bound with color coded pages and a bookmark included. It is a pleasure to hold and read.