The Linux Programmer's Toolbox by John Fusco. Allows your Linux usefulness to go from 0-60 in six seconds. Not totally exhaustive on all tools Linux, but it's brilliant for giving you an up to date map of the Linux development environment. Not only that, but it can give you a greater understanding of any development environment which uses make or GCC. I really can't recommend this book highly enough - it's so well written and laid out that I use it regularly as a reference manual. Not only does it cover many of the useful Linux tools (and shows you how to look for the rest), it covers how the kernel works, gnu make systems, debugging and has a nice comprehensive guide to using Vim and Emacs effectively (although, sadly, it doesn't say which is best - but I think you know the answer to that).
The Art of Unix Programming by Eric S. Raymond (Link is to the full book text). Once you have all the tools, you'll want to know how to use them. Not only does this book give you the why behind the what of Linux - explaining the design and implementation mechanisms that have shaped it, it gives an excellent narrative on the history and context in which these mechanisms evolved from someone who was there at the time. Make sure you absorb his 17 basics of the Unix philosophy, don't trust yourself to touch a line of code until you do! I'll repeat them here, just in case you miss them:
The Art of Happiness: A Handbook for Living, by the Dalai Lama. Not a technology book, but it has to be said some of the greatest challenges I've had in my working environment is not the code or the technology, but the people.
This book gives a good grounding in principles giving you a greater knowledge of oneself and others - based around the idea that compassion for others is the main source of happiness.
Useful for those times when you need to take a deep breath and stand back....