Yesterday, I wrote a post about how I'm learning Ruby in public. There are many sources I'm finding pretty useful. I'm going to list five of them here:
Ruby for beginners is an online course/book for those who are starting learning Ruby. They use a pretty simple language. Even people without programming experience can understand it.
It was created by Ruby Monstas, a Berlin group about Ruby.
The official Ruby website has a quick guide to get started with Ruby in twenty minutes. It's straight-forward and a good way to start learning the basics.
Also, remember to check out the official docs. I found them a little bit confusing, though.
Codecademy's course isn't very extensive but it will help you gain familiarity with Ruby and basic programming concepts.
JavaTPoint has extensive programming tutorials from many languages, including Ruby. I found their tutorials very easy to read and they contain a wide range of topics.
Learn Ruby Online is a course "intended for everyone who wishes to learn the Ruby programming language, whether you are an experienced programmer or not." They also provide some interactive exercises, so you can easily practice what you're learning.
I've added all those resources to a list of Ruby courses on Zoonk. It's an open, collaborative list. Feel free to add more resources you find useful for learning Ruby.