"Quantum Concepts in Physics: An Alternative Approach to the Understanding of Quantum Mechanics" by Malcolm Longair (2013)
This book, intended to be a compliment to (but not substitute for) standard courses and texts on quantum mechanics, presents quantum mechanics from a historical perspective at about the level of a senior undergraduate. At 400 pages, it is much more digestible than the multi-volume comprehensive work of Mehra and Rechenberg. I have thoroughly enjoyed the parts that I have read.
"Differential Geometry and Lie Groups for Physicists" by Marian Fecko (2006)
Fecko has lots of examples given as short exercises, which might not be a likable style for everyone, but I certainly have learned stuff from it.
"Lectures on Quantum Theory: Mathematical and Structural Foundations" by Chris Isham (1995)
Twenty years ago, I slowly went through this little book, line-by-line. This is one of the very few books for which I have done this. I think that this book, which is not an axiomatic presentation of quantum mechanics, should be read by more physics grad students.
"Quantum Field Theory: A Tourist Guide for Mathematicians" by Gerald Folland (2008)
Although Folland doesn't cover as much as physics texts such as Schwartz or Peskin and Schroeder, Folland does cover a lot more than most rigourous math books on quantum field theory. Folland uses mathematical rigour where possible, and where physicists' quantum field theory calculations have yet to be made mathematically rigourous, Folland states the mathematical difficulties, and then formally pushes through the physicists' calculations. I would be interested in hearing some opinions of physics on this book. I think that book states more clearly some of the standard aspects of quantum field, but I know little about quantum field theory, and I could be wrong.
As a side note, I am trying (sporadically) to learn a little more about quantum field theory, but someone close to me thinks that my efforts are futile.