General Programming

Programming Pearls; Jon Louis Bentley; Paperback.
More Programming Pearls: Confessions of a Coder; Jon Louis Bentley; Paperback. (Out of print)

"These are indeed collections of gorgeous pearls. Nothing Python-related there (it didn't exist at the time, so it's a pretty good excuse), and most of it really has to do with the crazy things you can do with pic, eqn and the like."

Karel++: A Gentle Introduction to the Art of Object-Oriented Programming; Joseph Bergin, Mark Stehlik, Richard Pattis; Paperback.

"One thing that helped with the concepts [of object-oriented programming] is this little book. The subtitle is 'A gentle introduction to the art of object-oriented programming', and it's just that, using C++. Even reading the first few chapters will help immensely."

The Mythical Man Month; Frederick P. Brooks, Jr.; Paperback.

Introduction to Algorithms; Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest; Hardcover.

The Elements of Programming Style; Brian W. Kernighan; Paperback.

The Art of Computer Programming Vol. 1: Fundamental Algorithms,
The Art of Computer Programming Vol. 2: Seminumerical Algorithms,
The Art of Computer Programming Vol. 3: Sorting and Searching, 3rd edition; Donald E. Knuth; Hardcover.

Covers algorithms in exhaustive (and exhausting!) mathematical detail.

Object-Oriented Software Construction; Bertrand Meyer; Paperback.