Design Patterns: Elements of Reusable Object-Oriented Software. This book is a must-have for design pattern. Every one who wants to develop OO software should read this book first. I believe you can learn a lot from this book no matter you are a C++ newbie or veteran.
Effective C++: 55 Specific Ways to Improve Your Programs and Designs (3rd Edition).
There are only two kinds of programmers in the world. One is the kind who have read this book, the other is the kind who haven't read this book.
Head First Design Patterns. Another famous and interesting book about design patterns. It is written in very intuitive way, just like the comic book. Lots of figures and illustration makes this book very easy to understand. I personally suggest, read this book, and then go to study the book written by Gang of Four.
Unix Network Programming, Vol. 1: The Sockets Networking API, Third Edition. A bestseller for UNIX network programming. If you are working in network-related projects, this book is the 1-st choice for you. It provides many simple examples that can help you understand the UNIX socket APIs. It's a good book not only for reference but also worth studying.
Advanced Programming in the UNIX(R) Environment. Richard Steven's another bestseller. This book gives us an in-depth knowledge about programming in the UNIX environment. The concepts in this book not only apply to the UNIX programming, but also applicable to the programming in other platform. Through this book, you can learn the imperative programming knowledge in the most robust and reliable platform in the history. If you are working in the UNIX environment, you must study this book, or, don't tell others that you know UNIX programming.