Sometimes the old adage rings true: the best things in life are free. If you've wanted to learn a little Ruby, but haven't been able to fit a programming course into your budget, don't worry. There are a number of places on the Web to begin your learning, without sacrificing money or quality.
One of the first versions of the venerable Programming Ruby (better known as the "Pickaxe Book") is available for free online. While it was written for Ruby 1.6 and was published in 2000, this can still be a very useful book for any beginning Ruby programmer. All of the fundamentals have gone unchanged, and all the code presented in this book still works! The authors (Dave Thomas, Andy Hunt and Chad Fowler) are respected and known Rubyists.
A one-man project, Mr. Neighborly's Humble Little Ruby Book is available free as HTML or a PDF, but also as a book from the on-demand publisher lulu.com. This book covers all the basics, and is more recent than the free version of the Pickaxe Book. Published in 2006, it covers the 1.8.x version of Ruby.
You have to like this one. Why's Poignant Guide to Ruby is Why's very unique take on learning Ruby. What would it be like if two cartoon foxes taught you how to program in Ruby? You're just going to have to read it to find out. You just have to trust me when I say it's worth it. Chunky bacon, anyone?
This text is aimed any someone who's never programmed before. Even the most basic concepts are explained well. This is more of a book on how to program that just happens to use Ruby its the programming language. This is a great resource for anyone starting from the ground up.
A quick tutorial on the Ruby homepage. It demonstrates some of Ruby's features, anyone can use this for a quick bootstrap in the Ruby language, or to see how things are done compared to other programming languages.
Harness the power of the Wiki! This Wikibook (a collection of Wikipages presented as a book) not only teaches you Ruby, but after you've mastered other areas of Ruby not presented in this book, you can go back and contribute new chapters or pages.
Another free book! Does the Ruby community ever stop producing free books? 29 full chapters of Ruby goodness is here for the reading.
One of the original Ruby documents. This has been around for quite a long time, since before Ruby was popular outside of Japan. In fact, this document was originally written in Japanese and was translated into English. It covers all the basics and has plenty of code examples.
An all-in-one Ruby documentation site. This site houses documentation for many versions of Ruby, documentation for some libraries, etc. This should be one of your bookmarks for quick access to all types of Ruby documentation.
PLEAC (the Programming Languages Examples Alike Cookbook) is the rosetta stone of programming languages. Originally created from the examples in the book the Perl Cookbook, PLEAC re-implements these short programs in as many programming languages as possible. This is an absolutely awesome resource if you know other programming languages and are learning Ruby. Simply look up how to do things in Ruby and compare them to the programming languages you do know. It's as easy as that!