;;; Source: NumberLines. EmacsWiki. <http://www.emacswiki.org/emacs/NumberLines> accessed 2010-1-26.

(defun numerotate-line ()
  (interactive)
  (let ((P (point))
	(max (count-lines (point-min) (point-max)))
	(line 1))
    (goto-char (point-min))
    (while (<= line max)
      (insert (format "%d " (* line 10)))
      (beginning-of-line 2)
      (setq line (+ line 1)))
    (goto-char P)))