Computer Science Books
Books identified as useful no matter how old they are, since they illustrate concepts that are still valid to computer science.
The Art of Computer Programming, Donald Knuth, 1973 (and earlier)
The Pragmatic Programmer, Andrew Hunt & Dave Thomas, 1999
Kernighan and Plauger's Software Tools.
Refactoring: Improving the Design of Existing Code. Martin Fowler, 1999
A Book on C, (first edition) by Al Kelley and Ira Pohl.
The Design of Everyday Things (Donald A Norman), first published in 1988.
The Visual Display of Quantitative Information, by Edward Tufte.
Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp. Peter Norvig/1992
The UNIX C Shell Field Guide -- Great read!
The UNIX Programming Environment by Kernghan & Pike
Fred Brooks' The Mythical Man-Month, 2nd ed. published 1995
Programming Perl (O'Reilly Camel book), 1995
Dragon Book by Alfred V. Aho, Ravi Sethi
"The C Programming Language" (K&R2) (1988) by Brian W. Kernighan and Dennis M. Ritchie.
Numerical Methods that Work.
Design Patterns Elements of Reusable Object-Oriented Software - GOF (1995)
Introduction to Algorithms, 2nd edition (2001) - MIT Press
Martin Fowler's "UML Distilled"
Introduction to Algorithms by Cormen, Leiserson, and Rivest
Links and cleanup forthcoming.
Stack Overflow (upvoted answers)