List of good, free online resources, categorized by subject. Add books, websites, apps, docs, repos, etc.

Unix

YAY!

Shell / Bash

• excellent short video tutorials on the basics of bash: http://pgbovine.net/command-line-tutorial.htm . highly recommended for folks who are totally new to the command line.
• intro to writing shell scripts: http://linuxcommand.org/lc3_writing_shell_scripts.php
• the linux command line by william shotts - excellent book for the new command line user. full text available for free at http://linuxcommand.org/tlcl.php.
• command line mystery!
• The Command Line Crash Course

Javascript

• Eloquent Javascript, one of the best books on the subject, with interactive tutorials.
• http://jsforcats.com/ - A+ short intro.
• Interactive code lessons Node School, some of which cover basic and advanced JS.
• Coderbyte - toy problems to practice your JavaScript (or any language) skills. (http://coderbyte.com/CodingArea/Challenges/).
• Paqmind - learning platform dedicated to programming and web development. Hundreds of exercises with solutions and explanations.
• JavaScriptIsSexy has some good information about JavaScript in some depth. For example, here's a post on scope and hoisting here.
• Learn JavaScript Design Patterns
• Clearinghouse of JavaScript resources - Superhero.js.
• NPM - Home to 100K open source javascript modules
• "Beginning Javascript" - nice book to begin javascript!
• Idiomatic JavaScript - JavaScript style guide
• Airbnb JavaScript Style Guide - another JavaScript style guide
• JavaScript Garden - documentation on JavaScript, available in different languages
• You Don't Know JS - Series of books diving deep into the core mechanisms of the JavaScript language.
• Fight Code - Engage in a death battle with your JavaScript powered robot.
• Untrusted - Learn Javascript to level up in an interactive game.
• Human JavaScript - Separate server concerns from client concerns, and write minimal, modular, and (most importantly) human-readable code.

Node.js

• Install Node.js
• Node.js API Reference
• Interactive code lessons Node School, many of which are Node.js specific.
• NPM - Home to 100K open source javascript modules
• Art of Node - A short introduction to Node.js.
• Node for Beginners - A list of resources for Node.js newbies.

Git & Github

• excellent short video tutorial on git: https://www.youtube.com/watch?v=u2rZLVWOWvs
• excellent short video tutorial on github: https://www.youtube.com/watch?v=3cMP4oBKO34
• Node School Git [Interactive Tutorials] (https://github.com/jlord/git-it)
• Try Git - Online interactive workshop.
• If the porcelain is confusing you, learning about the plumbing might help!

IRC

• https://www.linode.com/docs/applications/messaging/using-irssi-for-internet-relay-chat - great guide on setting up irc so that you're always online.

HTML5 and Front-end Web Development

• Mozilla's Developer Network MDN provides a great reference for open web standards, Javascript, the DOM, and general web development.
• Articles and demos of HTML5 APIs HTML5 Rocks
• Browserify, the modular, front-end build complex powered by NPM
• Require Bin - build and test browserify compatible front-end modules

CSS

• http://learnlayout.com/clearfix.html - short intro to css layouts with hamsters.

Python

• Learn Python.
• Python Tutor
• Codecademy Python track
• People really like Learn Python The Hard Way Note - this is a little outdated--learning Python 3 is more important now than when this was written. It's still a useful resource, though.

Regular Expressions

• Mastering Regular Expressions by Jeffrey Friedl. full text here.
• Regular Expressions on MDN
• Learn Regex the Hard Way
• http://www.regexr.com/ - excellent interactive site for trying out and learning regex.
• https://regex101.com - another interactive regex site. Has a good explainer.

Mac OSX

• homebrew - package management for OSX
• A helpful repo for installing build tools for OSX development

Tutorials About Everything

• Bento has curated tutorials about HTML, CSS, JavaScript, Databases, and more!
• Khan Academy - Free practice exercises and videos about a variety of subjects! Includes sections on math, computer science (algorithms, cryptography and information theory), and computer programming tutorials for JavaScript, HTML, and CSS
• Exercism is similar to nodeschool, in that it is run from the command line, and the lessons are contributed by community members. Lessons are available for several languages, including JavaScript. No node lessons (use nodeschool to learn you the node.js!).
• codewars is similar to Exercism, but in the browser.

What's programming all about?

• some things to get you started thinking about the kinds of things computers do: http://pgbovine.net/computer-science.htm

Roomba docs

• irobot create manual
• irobot create open interface docs

Working with sources of data

• How to make a node app with the LocalWiki API (see: http://localwiki.org and https://localwiki.org/api/v4/): http://learnjs.io/blog/2014/02/11/hyperquest-director-handlebars-example-app/
• Crime doesn't climb - great writeup that walks you through doing a data analysis and visualization with a source of open data. uses node.

More Free Learning Resources

• reSRC: Victor Felder's Github repository - This Open Source project is maintained on Github as a master reference list of programming/Computer Science books and resources released under a Creative Commons license, and is available in other languages as well. (Check with the author, publisher, and or content creator's website for details on what the Creative Commons license covers).

• reSRC: Intro Page - Victor Felder's Github intro page, which links free podcasts, JavaScript frameworks, interactive resources, and software testing books.

Disclaimer: The software testing books point to another repo maintained by another person. Please check with the author, creator or publisher to verify the copyright terms on these books.