This bit of code adds a bitmap to the fringe that marks the current mark.  Handy when popping off the ring.

  ;; overlay an arrow where the mark is
  (defvar mp-overlay-arrow-position)
  (make-variable-buffer-local 'mp-overlay-arrow-position)
  (add-to-list 'overlay-arrow-variable-list  'mp-overlay-arrow-position)

  (defun mp-mark-hook ()
    ;; (make-local-variable 'mp-overlay-arrow-position)
    (unless (or (minibufferp (current-buffer)) (not (mark)))
      (set
       'mp-overlay-arrow-position
       (save-excursion
         (goto-char (mark))
         (forward-line 0)
         (point-marker)))))

  (add-hook 'post-command-hook 'mp-mark-hook)


If you want to change the bitmap, defaults to the left arrow, change the attribute for mp-overlay-arrow-position:

  (put 'mp-overlay-arrow-position 'overlay-arrow-bitmap 'right-triangle)

or you can make a custom one, here's mine:

  ;; make the mark fringe bitmap look cool dude
  (define-fringe-bitmap 'mp-hollow-right-arrow [128 192 96 48 24 48 96 192 128] 9 8 'center)
  (put 'mp-overlay-arrow-position 'overlay-arrow-bitmap 'mp-hollow-right-arrow)