Ruby homepage http://www.ruby-lang.org/en/
QuickRef: http://www.zenspider.com/Languages/Ruby/QuickRef.html
How to install Ruby1.9 on Ubuntu: http://extralogical.net/2009/07/ruby-one-niner/;

Interactive Ruby: http://tryruby.hobix.com/
Ruby tutorial: http://pine.fm/LearnToProgram/
Ruby essentials: http://www.techotopia.com/index.php/Ruby_Essentials

Ruby one-liners: http://www.fepus.net/ruby1line.txt
Programming Ruby: http://www.ruby-doc.org/docs/ProgrammingRuby/

Brian Schröder's immersive Ruby course : pdf [2.2Mb]

ruby-debug: http://pivots.pivotallabs.com/users/chad/blog/articles/366-ruby-debug-in-30-seconds-we-don-t-need-no-stinkin-gui- |   

Gtk Programming: http://ruby-gnome2.sourceforge.jp/hiki.cgi?tut-gtk-intro

Glade and Gtk: http://www.micahcarrick.com/12-24-2007/gtk-glade-tutorial-part-1.html#Adding_Widgets_to_the_GtkWindow | http://xrob.wordpress.com/2007/04/20/creating-a-gui-application-using-glade-and-ruby/
NetBeans: http://www.netbeans.org/kb/60/screencasts.html