Implementing Lean Software Development: From Concept to Cash by Mary Poppendieck & Tom Poppendieck is one of my favourite books right now. The book is not a big selection of agile recipes you can apply to different situations, instead the Poppendiecks take us back to first principles. They show how these principles drive the different agile practice. Ultimately they demonstrate how to think about your software development and what it means to become more effective. If you have decided to embark on making software development better, then this book can help you choose what it most important and what to do about it. The authors cover a history of lean and the seven principles of lean software development, ripped from their first book (Lean Software Development). The meat of the book covers off value, waste, speed, people, knowledge, quality, partners, and the journey ahead.
A couple of things made the book different for me: firstly, it is a great mix of sage advice, first principles from the grandfathers of lean, real-life stories and practical exercises. Secondly, it really covers the full value stream from your first ideas about software to ringing up the sale.