Pretty much every Emacs user knows of the *scratch* buffer - after all it’s always present when you start your Emacs. If you’ve set inhibit-startup-screen to t (which I recommend) it will even be the very first buffer see each time you fire up your beloved editor (unless you alter initial-buffer-choice, that is).

The scratch buffer was conceived a scratchpad for notes and Emacs Lisp experiments and a lot of Emacs users find it quite handy. On the other hand - even more users don’t really write Emacs Lisp and probably find little value in this buffer.

One little know fact about the *scratch* buffer is that its initial major mode (by default it’s lisp-interaction-mode) is not hardcoded and you can alter it. If you’re a Ruby developer you might opt to make it use ruby-mode by default:

(setq initial-major-mode 'ruby-mode)

If you do this I’d also advise you to change the buffer’s initial contents. By default they are:

;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.

For Ruby something like this might be better:

(setq initial-scratch-message "\
# This buffer is for notes you don't want to save, and for Ruby code.
# If you want to create a file, visit that file with C-x C-f,
# then enter the text in that file's own buffer.")

Or you can simply set initial-scratch-message to nil and be done with it.