README            this file
inf-ruby.el       program to run ruby under emacs
rdoc-mode.el      RDoc mode for emacs
ruby-mode.el      ruby mode for emacs
ruby-style.el     Ruby's C/C++ mode style for emacs
rubydb2x.el       ruby debugger support for emacs 19.2x or before
rubydb3x.el       ruby debugger support for emacs 19.3x or later
ruby-electric.el  emacs minor mode providing electric commands
ruby-additional.el ruby-mode extensions yet to be merged into Emacs

Check out https://github.com/ruby-debug/ also.