The Bastards Book of Ruby
This page covers the following topics related to Ruby : The Fundamentals, Installation, Tweet Fetching, Style, Conventions, and Debugging, Numbers, Strings, Variables, Methods, RubyGems, If and Else, Loops, Collections, Enumerables, File input/output, Reviewing Tweet Fetching, Supplementals, Design and Theory, The Projects.
Author(s): ruby.bastardsbook.com
NA Pages 
Ruby Programming by Wikibooks.org
This book is currently broken down into several sections and is intended to be read sequentially. Topics covered includes: Notation conventions, Basic Ruby, Ruby Semantic reference, Built in Classes, Standard Library.
Author(s): Wikibooks.org
NA Pages
This book is the only Rails book that does test-driven development the entire time, an approach highly recommended by the experts but which has never been so clearly demonstrated before. Finally, by including Git, GitHub, and Heroku in the demo examples, the author really gives you a feel for what it’s like to do a real-world project. The tutorial’s code examples are not in isolation.
Author(s): Michael Hartl
NA Pages
