(require 'column-marker)

(defun set-column-marker ()
  (column-marker-1 73)
  (column-marker-2 81))

(add-hook 'c-mode-hook          'set-column-marker)
(add-hook 'emacs-lisp-mode-hook 'set-column-marker)
(add-hook 'html-mode-hook       'set-column-marker)