- Repl.it : A ruby console in the web. It runs version 1.8.7 so it can present some compatibility issues, but it's great for when you need to write and run a program on the fly.
- Rubular: "a Ruby regular expression editor". From Socrates.
- Mozilla Developer Network: a kickass collection of useless webdev resources and tutorials: HTML, CSS, APIs, DOM, etc.
- http://www.cheat-sheets.org/ : Holy shit there are so many of them.
- Project Euler: Like Coderbyte, but this one is more math focused. Very cool.
- Rubeque: "Rubeque is a place to hone your Ruby skills by solving small Ruby problems while competing against other Rubyists."
- List of freely available programming books. It's a fucking huge list. Seriously. Eat up.
- Learn Vim Progressively: tl;dr: You want to teach yourself vim (the best text editor known to human kind) in the fastest way possible.
- The Linux Command Line by William Shotts: In addition to the basics of command line use and shell scripting, The Linux Command Line includes chapters on many common programs used on the command line, as well as more advanced topics.