(Also have a look at EbookFoundation/free-programming-books which has a far greater collection).
- PHP Essentials
- Practical PHP Programming (wiki containing O'Reilly's PHP In a Nutshell)
- Symfony2
- Zend Framework: Survive the Deep End
- Java Application Development on Linux by Carl Albing and Michael Schwarz(PDF)
- How to Think Like a Computer Scientist
- The Java EE6 Tutorial (PDF)
- Java Thin-Client Programming
- Sun's Java Tutorials
- Thinking in Java
- OSGi in Practice (PDF)
- Category wise tutorials - J2EE
- Introduction to Programming Using Java - David J. Eck
- Building Skills in Python Version 2.5
- Byte of Python
- Data Structures and Algorithms in Python
- Dive into Python
- Dive into Python 3
- The Django Book
- How to Think Like a Computer Scientist: Learning with Python
- Invent Your Own Computer Games With Python
- Learn Python The Hard Way
- Natural Language Processing with Python
- Python Bibliotheca
- Python for Fun
- Snake Wrangling For Kids
- Think Python (PDF)
- Thinking in Python
- Crockford's JavaScript
- Eloquent JavaScript
- Essential Javascript & jQuery Design Patterns for Beginners
- JavaScript Essentials
- jQuery Fundamentals (starts with JavaScript basics)
- Mozilla Developer Network's JavaScript Guide
- Developing Time-Oriented Database Applications in SQL
- Use The Index, Luke!: A Guide To SQL Database Performance
- Learn SQL The Hard Way
- Beej's Guide to Network Programming
- Beej's Guide to C Programming
- The C book
- C++ Annotations
- C++ GUI Programming With Qt 3
- CS106X Programming Abstractions in C++
- Essential C
- Introduction to Design Patterns in C++ with Qt 4 (PDF)
- Learn C the hard way
- Matters Computational: Ideas, Algorithms, Source Code, by Jorg Arndt
- The new C standard - an annotated reference
- Object Oriented Programming in C (PDF)
- Software optimization resources by Agner Fog
- Thinking in C++, Second Edition
- Also see: The Definitive C++ Book Guide and List
- DirectX manual (draft)
- Learning Modern 3D Graphics Programming (draft)
- GPU Gems
- GPU Gems 2 - ch 8,14,18,29,30 as pdf
- GPU Gems 3
- Graphics Programming Black Book
- ShaderX series
- 97 Things Every Programmer Should Know
- Algorithms and Data-Structures (PDF)
- Algorithms (draft)
- The Architecture of Open Source Applications
- The Art of Unix Programming
- Best Kept Secrets of Peer Code Review
- Binary Trees
- The Cathedral and the Bazaar
- Clever Algorithms
- Communicating Sequential Processes (PDF) - Tony Hoare
- Compiler Construction (PDF)
- Computer Musings (lectures by Donald Knuth)
- Data Structures and Algorithms: Annotated Reference with Examples
- Database Fundamentals (PDF)
- Data-Intensive Text Processing with MapReduce (PDF)
- The Definitive Guide to Building Code Quality
- Designing Interfaces by Jennifer Tidwell
- Digital Signal Processing For Engineers and Scientists
- Domain Driven Design Quickly
- Don't Just Roll the Dice
- Essentials of Metaheuristics by Sean Luke
- Essential Skills for Agile Development
- A Field Guide To Genetic Programming
- Flow based Programming
- Foundations of Computer Science - Al Aho and Jeff Ullman
- Foundations of Programming
- Getting Real
- Getting started with Open source development (PDF)
- The Great Tree List Recursion Problem
- Guide to the Software Engineering Body of Knowledge
- How Computers Work
- How to Design Programs
- How to Think Like a Computer Scientist
- How to Write Parallel Programs
- How to write Unmaintainable Code
- I Am a Bug
- An Introduction to the Theory of Computation
- Introduction to Functional Programming (class lectures and slides)
- Introduction to Information Retrieval
- Is Parallel Programming Hard, And, If So, What Can You Do About It?
- Learn to Program
- Let's Build a Compiler
- Linkers and loaders
- Linked List Basics
- Linked List Problems
- Mathematical Logic - an Introduction (PDF)
- Matters Computational
- Mining of Massive Datasets
- NASA Manager Handbook for Software Development (PDF)
- NASA Software Measurement Handbook
- Object-Oriented Reengineering Patterns
- Online Course Materials
- OO Design
- Operating Systems and Middleware (PDF and LaTeX)
- Patterns and Practices: Application Architecture Guide 2.0
- Patterns of Software: Tales from the Software Community (PDF)
- Planning Algorithms
- PNG: The Definitive Guide
- Pointers And Memory
- Producing Open Source Software
- Programming Languages: Application and Interpretation
- Programming Methodology
- Programming Pearls
- Project Oberon (PDF)
- Seamless Object-Oriented Software Architecture
- Security Engineering
- Structure and Interpretation of Computer Programs
- Summary of the GoF Design Patterns
- The Little Book of Semaphores
- The TCP/IP Guide
- Think Stats: Probability and Statistics for Programmers (PDF, code written in Python)
- Type Theory and Functional Programming
- Understanding IP Addressing: Everything you ever wanted to know (PDF)
- Programming from the Ground Up (PDF)
- Paul Carter's Tutorial on x86 Assembly
- Software optimization resources by Agner Fog
- Advanced Bash-Scripting Guide
- Bash Guide for Beginners by Machtelt Garrels
- Lhunath's Bash Guide
- The Command Line Crash Course (also a Powershell reference)
- See .NET below
- Getting started with DB2 Express-C (PDF)
- Getting started with IBM Data Studio for DB2 (PDF)
- Getting started with IBM DB2 development (PDF)
- The F# Survival Guide
- F Sharp Programming in Wikibooks
- Real World Functional Programming (MSDN Chapters)
- Advanced Linux Programming
- GNU Autoconf, Automake and Libtool
- GTK+/Gnome Application Development
- The Linux Development Platform (PDF)
- Linux Device Drivers by Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman
- The Linux Kernel Module Programming Guide
- Secure Programming for Linux and Unix
- Common Lisp the Language, 2nd Edition
- Common Lisp: A Gentle Introduction to Symbolic Computation - David S. Touretzky
- Common Lisp Quick Reference
- Let Over Lambda - 50 Years of Lisp
- Natural Language Processing in Lisp
- On Lisp
- Practical Common Lisp
- Successful Lisp: How to Understand and Use Common Lisp - David Lamkins
- Sketchy LISP - Nils Holm
- Programming In Lua (for version 5)
- Better Builds with Maven
- Maven by Example
- Maven: The Complete Reference
- Repository Management with Nexus
- Developing with Eclipse and Maven
- See .NET below
- C# Essentials
- C# Programming - Wikibook
- C# Yellow Book (intro to programming)
- Charles Petzold's .NET Book Zero
- Data Structures and Algorithms with Object-Oriented Design Patterns in C#
- Entity Framework
- Moving to Microsoft Visual Studio 2010
- Nemerle
- Programmer's Heaven C# School Book (covers C# 1.0 and 2.0)
- Threading in C#
- Visual Basic Essentials
- Visual Studio Tips and Tricks (VS 2003-2005 only)
- Programming in Oberon (PDF)
- Introduction to Objective Caml (PDF)
- Objective Caml for Scientists (first chapter only)
- Unix System Programming in OCaml
- Developing Applications With Objective Caml
- Oracle's Guides and Manuals
- PL/SQL Language Reference
- PL/SQL Packages and Types Reference
- Steven Feuerstein's PL/SQL Obsession - Videos and Presentations
- Using Perl 6 (work in progress)
- Beginning Perl
- Embedding Perl in HTML with Mason
- Essential Perl
- Extreme Perl
- Higher-Order Perl
- The Mason Book
- Modern Perl 5
- Perl & LWP
- Perl for the Web
- Perl Free Online EBooks (meta-list)
- Perl The Hard Way
- Practical mod_perl
- Web Client Programming with Perl
- Adventure in Prolog
- Applications of Prolog
- Building Expert Systems in Prolog
- Introduction to Prolog for Mathematicians
- Learn Prolog Now!
- Logic, Programming and Prolog (2ed)
- Natural Language Processing in Prolog
- Natural Language Processing Techniques in Prolog
- Prolog Programming A First Course
- Prolog Techniques
- Simply Logical
- Visual Prolog 7.2 for Tyros
- Learn Ruby the hard way
- MacRuby: The Definitive Guide
- Mr. Neighborly's Humble Little Ruby Book
- Programming Ruby
- Ruby Best Practices
- Why's (Poignant) Guide to Ruby (mirror)
- Exploring Lift (published earlier as "The Definitive Guide to Lift", PDF)
- Lift
- Pro Scala: Monadic Design Patterns for the Web
- Programming in Scala, First Edition
- Programming Scala
- Scala By Example (PDF)
- A Scala Tutorial for Java programmers (PDF)
- Xtrace
- Concrete Abstractions: An Introduction to Computer Science Using Scheme
- The Scheme Programming Language Edition 3, Edition 4
- Simply Scheme: Introducing Computer Science
- Dynamic Web Development with Seaside
- Free Online Smalltalk Books (meta-list)
- Squeak By Example (Smalltalk IDE)
- A Byte of Vim
- Vim Recipes
- Vi Improved -- Vim by Steve Oualline
- Agile Android Software Development - Etienne Savard (PDF, epub, mobi - need email confirmation)
- Building Android Apps with HTML, CSS, and JavaScript (Phased out by Oreilly)
- Learning Android (Phased out by Oreilly)