Kite - Kite helps you write code faster by bringing the web's programming knowledge into your editor.
Codewell.cc - Improve your HTML and CSS skills by practicing on real world design templates.
Remote Duck - Stranger on the Internet that can help you debug your code
Good Code - Free front end coding challenges
Sublime Tutor - Learn Sublime Text from a tutor who sits inside the editor
One Degree - The Human Search Engine