In preparation for the first meeting of the Piedmont Ruby user group, I've assembled a list of what I consider the essential books and other resources for learning and improving your knowledge of Ruby and its associated frameworks/tools. What follows is a general list of resources for beginners and experienced Rubyists, respectively. As of this post, the latest software releases are Ruby 2.1.1 and Rails 4.2.x.
Full disclosure: Some of these are Amazon referral links that support this blog.
Bolded resources are free and/or open source resources.
There are plenty of additional resources, and everyone has their favorites. It's my belief that the above resources will give you a great base knowledge of all that Ruby has to offer, with additional knowledge of modern Rails.
Ruby hacker, gamer, mathematician, father, etc.