The Well-Grounded Developer

Going along with the theme of some of the "Well-Grounded" books that had come out in recent years, I wanted to share a list of books and resources that have helped me become a better programmer. More importantly, however, I am curious to hear the resources or books that have contributed to you being the "Well-Grounded Programmer". Here is my "Well-Grounded Developer" reading list: Illustrated C# 2012 (Or previous versions, 2010, etc.) This is the one book that has enabled me to understand the why and how about the C# programming language. For example: This book has a clear explanation of why you would use an Interface. Next book.. Practical Object-Oriented Design in Ruby This is the first book that I have read regarding Object Oriented Design that has made sense to me. The author presents this material in an easily understandable fashion with real world examples. Example: I finally understood Dependency Injection after reading this book. So there is my list towards becoming a "Well-Grounded Developer". How about you?