Fancy GUI Rails-friendly emacs install with functionality similar to Acumen Brands' dotmatrix for OSX.

gistfile1.el

;; extend the load-path
(let ((default-directory "~/.emacs.d/lisp/"))
    (normal-top-level-add-to-load-path '("."))
    (normal-top-level-add-subdirs-to-load-path))

;; package archives, MELPA and ELPA
(require 'package)
(add-to-list 'package-archives
             '("melpa" . "http://melpa.milkbox.net/packages/") t)
(when (< emacs-major-version 24)
  (add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/")))
(package-initialize)

(setq package-archives '(("gnu" . "http://elpa.gnu.org/packages/")
                         ("marmalade" . "http://marmalade-repo.org/packages/")
                         ("melpa" . "http://melpa.milkbox.net/packages/")))

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(ansi-color-names-vector ["#242424" "#e5786d" "#95e454" "#cae682" "#8ac6f2" "#333366" "#ccaa8f" "#f6f3e8"])
 '(custom-enabled-themes (quote (deeper-blue))))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )

;;; Ruby/Rails development
;; RVM support
;; Ruby Version Manager
(require 'rvm)
(rvm-use-default)

;; automatically add 'end' after class, module, def etc.
;; automatically pair braces, single and double quotes
(require 'ruby-electric)
(add-hook 'ruby-mode-hook 'ruby-electric-mode)

;; Rails support
;; jump to corresping model/view/controller,
;; find file in project, etc
(require 'rinari)
(add-hook 'ruby-mode-hook 'rinari-minor-mode)

;; whitespace-mode for Ruby code
;; helps with cleaning out unnecessary white space
;;(add-hook 'ruby-mode-hook 'whitespace-mode)

;; rspec
;; run specs in a compilation buffer
(add-to-list 'load-path "~/.emacs.d/vendor/rspec-mode")
(require 'rspec-mode)

;; cucumber
;; run features in a compilation buffer
;;(add-to-list 'load-path "~/.emacs.d/vendor/cucumber-mode")
(require 'feature-mode)
(add-to-list 'auto-mode-alist '("\.feature$" . feature-mode))

;; syntax highlighting etc. for HAML
(require 'haml-mode)

;; display strings representing colors with
;; the color they represent as background
(add-to-list 'load-path "~/.emacs.d/vendor/jd-el")
(require 'rainbow-mode)
(add-hook 'css-mode-hook 'rainbow-mode)

steps

 - install emacs via http://emacsformacosx.com/ (do not install homebrew emacs)
 - open and close emacsforosx
 - copy config to ~/.emacs
 - mkdir ~/.emacs.d/lisp
 - open emacs (ignore errors)
 - M-x package-install RET rvm
 - M-x package-install RET rinari
 - M-x package-install RET ruby-electric
 - M-x package-install RET rspec-mode
 - M-x package-install RET feature-mode
 - M-x package-install RET haml-mode
 - M-x package-install RET rainbow-mode
 - close and re-open emacs
 - happy hacking!