Free Electronic Books Online

(I got these off of http://www.cc.gatech.edu/~kaotech)

Literature
Project Gutenberg - Public domain works (Shakespeare, etc)
Literature Project - Classics
Dante's Inferno
The Complete Worls of Edgar Allan Poe
Beowulf
The Interpretation of Dreams by Sigmund Freud
Homer's Iliad &Odyssey
The Autobiography of Charles Darwin
Darwin's The Origin of Species
The Egyptian Book of the Dead

Graphics Programming
OpenGL Programming Guide
OpenGL Reference Manual
Pixar's RenderMan Reference (v. 3.2)

Algorithms
Numerical Recipes in C
Numerical Recipes in Fortran 77
Numerical Recipes in Fortran 90
Handbook of Applied Cryptography

Programming
Structure and Interpretation of Computer Programs
Watch What I Do: Programming By Demonstration
How To Think Like A Computer Scientist (C++)
How To Think Like A Computer Scientist (Java)
How To Think Like A Computer Scientist (Python)
Thinking in C++
or here (translations: Spanish, Italian)
Thinking in Java or here (translations: Russian, French, Spanish, Portugese, Slovak)
Thinking in Patterns
Programming Ruby

Practical Artificial Intelligence Programming in Java
Loving Lisp, or the Savy Programmer's Secret Weapon
Principles of Object-Oriented Programming in Java
Various books on the Ada programming language
Advanced Linux Programming
Linux Kernel Module Programming Guide
Java AWT Reference from the O'Reilly Online Catalog
The Unix-Haters Handbook

Web

Web Client Programming with Perl
CGI Programming on the World Wide Web

Medical
Exeter Medical Library online textbooks
freemedicaljournals.com

Physics
A Heat Transfer Textbook
Lessons in Electric Circuits