How to move forward and backward in Emacs' mark ring

Here's a solution I just finished spending way too much time on. The difference between this and the other solutions is it works across buffers, ie it works on the 'global-mark-ring'. My goal was to emulate history browsing similar to Eclipse or IntelliJ. I bind it to M-left and M-right, obviously you can choose different keys for this.

(defun marker-is-point-p (marker)
  "test if marker is current point"
  (and (eq (marker-buffer marker) (current-buffer))
       (= (marker-position marker) (point))))

(defun push-mark-maybe () 
  "push mark onto `global-mark-ring' if mark head or tail is not current location"
  (if (not global-mark-ring) (error "global-mark-ring empty")
    (unless (or (marker-is-point-p (car global-mark-ring))
                (marker-is-point-p (car (reverse global-mark-ring))))
      (push-mark))))


(defun backward-global-mark () 
  "use `pop-global-mark', pushing current point if not on ring."
  (interactive)
  (push-mark-maybe)
  (when (marker-is-point-p (car global-mark-ring))
    (call-interactively 'pop-global-mark))
  (call-interactively 'pop-global-mark))

(defun forward-global-mark ()
  "hack `pop-global-mark' to go in reverse, pushing current point if not on ring."
  (interactive)
  (push-mark-maybe)
  (setq global-mark-ring (nreverse global-mark-ring))
  (when (marker-is-point-p (car global-mark-ring))
    (call-interactively 'pop-global-mark))
  (call-interactively 'pop-global-mark)
  (setq global-mark-ring (nreverse global-mark-ring)))

(global-set-key [M-left] (quote backward-global-mark))
(global-set-key [M-right] (quote forward-global-mark))

Unlike previous answers, this one does only exactly what was asked: the reverse of C-u C-SPC. I find it the most useful.

(defun unpop-to-mark-command ()
  "Unpop off mark ring. Does nothing if mark ring is empty."
  (interactive)
      (when mark-ring
        (setq mark-ring (cons (copy-marker (mark-marker)) mark-ring))
        (set-marker (mark-marker) (car (last mark-ring)) (current-buffer))
        (when (null (mark t)) (ding))
        (setq mark-ring (nbutlast mark-ring))
        (goto-char (marker-position (car (last mark-ring))))))

Comparing to the answer by scottfrazer, this command has a subtle difference of how it moves the cursor and mark, which more accurately mirrors C-u C-spc, and it does not require that the previous command was a unpop/pop-to-mark-command.