RubyGems User Guide
Publisher: RubyGems.org 2010
RubyGems is the premier ruby packaging system. It provides: A standard format for distributing Ruby programs and libraries; An easy to use tool for managing the installation of gem packages; A gem server utility for serving gems from any machine where RubyGems is installed; A standard way of publishing gem packages.
Download or read it online for free here:
by Jeremy McAnally
Covers the Ruby language from the very basics to the advanced topics. Written in a conversational narrative rather than like a dry reference book, Mr. Neighborly's Humble Little Ruby Book is an easy to read, easy to follow guide to all things Ruby.
by Karthikeyan A K - Mind As Lab
With this unique hands-on learning experience, you'll discover how Ruby takes care of all the details for you, so you can simply have fun and get more done with less code. This book is written for GNU/Linux (Debian distro) users ...
by why the lucky stiff
This is just a small illustrated online-only Ruby book. It won't crush you. It's light as a feather (because I haven't finished it yet--hehe). And there's a reason this book will stay light: because Ruby is simple to learn.
by Mark Slagell
Ruby is an easy object oriented language: it is designed to be easily read and written. This User's Guide will get you started at invoking and using ruby, and give you insights into ruby's nature that you may not get from the reference manual.