Blink is a book about “thinking without thinking” but really, it’s about how the vast majority of thinking works. The insight in this book is especially useful when dealing with people who aren’t particularly well equipped to discuss their subconscious reactions to something relatively subjective…like design.
Linchpin is the book that pulls together a lot of threads that Seth Godin has laid out there in the past, in books like Purple Cow, Tribes, and The Dip. Linchpin tells you, in no uncertain terms, that these things aren’t about brands or leadership or challenges, but about love. Really, this book is a love letter to loving your work.
Merlin Mann is a productivity guru that wants you to stop worrying about rearranging deck chairs and start finding the time and focus to do your best creative work. He’s funny, zany, and prone to a really obtuse but ultimately insightful analogy. He’s internet-famous for things like Inbox Zero and The Hipster PDA; but he’s also way awesomer than that.
100 Things Every Designer Needs to Know About People is a list of all the bits of psychology that they should be teaching in design school. It’s neatly organized, easy to refer to, and easily the best $30 I’ve spent on books in the last few years. If you’re even remotely interested in improving the effectiveness of your designs through an understanding of cognition, this is a great place to start.