Things That Newcomers to Ruby Should Know - List of most common problems in Ruby, in HTML, text. Table of contents, descriptions, code samples, links. By Bill Tjokroaminata. - http://books.rubyveil.com/books/ThingsNewcomersShouldKnow/
RubyCocoa Resources - Documentation and examples, as digital books, for RubyCocoa, a bridge between Ruby and Objective-C, a way to make desktop programs with Ruby. - http://www.rubycocoa.com/
A Practical Introduction to Ruby: First Steps - Beginners introduction, on installing Ruby, and writing a first simple script. - http://coolnamehere.com/geekery/ruby/rubytut/part01.html
Try Ruby - Beginner's basic tutorial, online, interactive, works in Web browser, has Ruby interpreter above with lessons below. - http://tryruby.hobix.com/
Ruby User's Guide - Original Japanese version by matz. First English translation by GOTO Kentaro and Julian Fondren. Further translation and editing by Mark Slagell. - http://www.rubyist.net/~slagell/ruby/
Learning Ruby - By Daniel Carrera. Introduces programming, Ruby, assumes familiarity with computers in Unix X Terminal environment, but not Ruby; simple descriptions, many screenshots. Unfinished, but well done and useful for what is done. - http://www.math.umd.edu/~dcarrera/ruby/0.3/
Ruby Embedded into C++ - Describes how to embed Ruby interpreter in C++, gives skeleton to build on, treats concepts of embedding, advanced topics like SWIG. Descriptions, code, diagrams, links, news. - http://metaeditor.sourceforge.net/embed/
Ruby-Doc.org - Ruby documentation project: links and downloads of programming information, on many aspects of Ruby. - http://www.ruby-doc.org/
Ruby FAQ - Questions and official answers on Ruby. - http://www.rubycentral.com/faq/