I'm putting together a list meant to encompass what I consider the canon of works that I find valuable and suggest others may as well. Many of them I haven't read myself because, to be fair, they tend to be pricey. I've got the means to acquire hard copies right now, so I'm methodically working through that process. There are, of course, other ways to ahem acquire them for those that are low on funds.
It is my aim to list books that won't age too terribly over time (or have been kept up to date by the author). The essay books, in particular, should hold up quite well.
I've acquired hard copies of the titles in bold
Structure and Interpretation of Computer Programs by Harold Abelson, Gerald Jay Sussman, Julie Sussman
Head First Design Patterns by Eric Freeman, Elisabeth Robson
Grokking Algorithms: An Illustrated Guide for Programmers and Other Curious People by Aditya Bhargava
The Pragmatic Programmer by Andrew Hunt
A Friendly Introduction to Software Testing by Bill Laboon
Refactoring by Martin Fowler
Code Craft by Pete Goodliffe
Working Effectively with Legacy Code by Michael Feathers
Practical Web Inclusion and Accessibility by Ashley Firth
Don't Make Me Think, Revisited: A Common Sense Approach to Web Usability by Steve Krug
Accessibility Handbook: Making 508 Compliant Websites by Katie Cunningham
Engineering as Practice
The Effective Engineer by Edmond Lau, Bret Taylor
The Nature of Software Development by Ron Jeffries
Programming Beyond Practices: Be More Than Just a Code Monkey by Gregory T Brown
Becoming a Better Programmer: A Handbook for People Who Care About Code by Pete Goodliffe
My Life in Code by Ellen Ullman
Joel on Software by Joel Spolsky
Geek Sublime by Vikram Chandra
The Mythical Man-Month: Essays on Software Engineering by Frederick Brooks Jr.
Code: The Hidden Language of Computer Hardware and Software by Charles Petzold
Computing: A Concise History by Paul E. Ceruzzi
High Performance Browser Networking by Ilya Grigorik
Once Upon an Algorithm: How Stories Explain Computing by Martin Erwig
The Art of Doing Science and Engineering: Learning to Learn by Richard W. Hamming, Bret Victor
Personal areas of expertise
This section includes a few works that are specific to the languages and tools I use. The books here are considerably less "canon" and a bit more transient.