split-buffer-by-defuns.el

; this defun ripped from http://www.emacswiki.org/emacs/narrow-indirect.el
(defun narrow-to-region-indirect-other-window (start end here text)
  "`narrow-to-region' in a cloned indirect buffer in the other window.
The indirect buffer is named the same as the current buffer,
except it is suffixed by `:text'.

Non-interactively:
START and END are the region beginning and end.
HERE is where to place the cursor, relative to START.
TEXT is prefixed by `:' and appended to the
 original buffer name.

See `clone-indirect-buffer'."
  (interactive
   (list (region-beginning) (region-end) (point) (and current-prefix-arg  (read-string "Buffer name: ")) nil 'MSGP))
  (if (and (= start end)  msgp)
      (message "Region is empty")
    (deactivate-mark)
    (let* ((buf  (concat (buffer-name) ":" text))
           (buf   (clone-indirect-buffer buf nil)))
      (with-current-buffer buf (narrow-to-region start end) (goto-char here))
      )))

;; not quite there yet, but
(defun split-this-defun ()
  (interactive)
  (save-excursion
    (let ((start (point)))
      (end-of-defun)
      (previous-line 1)
      (let ((name (c-defun-name)))
        (end-of-defun)
        (next-line 1)
        (narrow-to-region-indirect-other-window start (point) start name)))))

(defun split-buffer-by-defuns ()
  (interactive)
  (save-excursion
    (let ((parent-point (point)))
      (goto-char (point-min))
      (while (not (= (point) (point-max)))
        (let ((start (point)))
          (end-of-defun)
          (previous-line 1)
          (let ((name (c-defun-name)))
            (end-of-defun)
            (next-line 1)
            (narrow-to-region-indirect-other-window start (point) parent-point name)))))))