scotch.io is a great source for tutorials (scotch.io/tag/node-js). I also recommend the Manning book on NodeJS, NodeJS in Action (manning.com/books/node-js-in-action). As the other comment said, NodeSchool is also a fantastic resource.

Here are some resources I follow:

• Mastering Node - Open Source Book
• NodeSchool
• The Art of Node
• Introduction to Node.js with Ryan Dahl
• NodeUp Podcast

Cheers!

Already some great answers here. I would like to add NodeGuide as a guide to an absolute beginner and Kyle Simpson's Real-time web with NodeJS as a comprehensive course for any one who wants to level up.

The Art of node is another great resource for understanding the core of node. Its pretty dry and dense but covers a lot of ground.

The following resources are really useful :

1. nodejs.org/en/docs
2. nodebeginner.org
3. tutorialspoint.com/nodejs