These are some of my personal favorites. If I have time I'll come back and mention a few more later on:
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Interface and interaction design:
Designing Visual Interfaces: Communication Oriented Techniques
Dont be put off by how old it is. It has rock solid advice and extremely well organized.
The Essential Guide to Interface Design
Very synthetic. Great compendium of design principles, human psychological traits, design patterns, etc. Awesome reference when you need to find something fast in order to stimulate your thinking about a specific topic.
About Face 3: The Essentials of Interaction Design
This is THE book for design principles. I have yet to find a principle in any other book that is not present in this one. Also has very a comprehensive design pattern library with great explanations that help you think for yourself.
For getting "the big picture":
Designing for the digital age
Covers all the typical steps in a UX project with very detailed explanations on how to structure the work, how to organize the team, how to deal with stakeholders, what questions to ask, what techniques to use to find great solutiones, etc.
Subject To Change: Creating Great Products & Services for an Uncertain World: Adaptive Path on Design
A must-read about design strategy and culture. This will help you question company paradigms and deal with business people.
The Elements of User Experience
To help you understand how different disciplines can fit together / complement each other in order to create great experiences.