Emacs Shell mode: how to send region to shell?

Ok, wrote an easy bit. Will probably spend some time to write a complete minor mode.

For time being the following function will send current line (or region if the mark is active). Does quite a good job for me:

(defun sh-send-line-or-region (&optional step)
  (interactive ())
  (let ((proc (get-process "shell"))
        pbuf min max command)
    (unless proc
      (let ((currbuff (current-buffer)))
        (shell)
        (switch-to-buffer currbuff)
        (setq proc (get-process "shell"))
        ))
    (setq pbuff (process-buffer proc))
    (if (use-region-p)
        (setq min (region-beginning)
              max (region-end))
      (setq min (point-at-bol)
            max (point-at-eol)))
    (setq command (concat (buffer-substring min max) "\n"))
    (with-current-buffer pbuff
      (goto-char (process-mark proc))
      (insert command)
      (move-marker (process-mark proc) (point))
      ) ;;pop-to-buffer does not work with save-current-buffer -- bug?
    (process-send-string  proc command)
    (display-buffer (process-buffer proc) t)
    (when step 
      (goto-char max)
      (next-line))
    ))

(defun sh-send-line-or-region-and-step ()
  (interactive)
  (sh-send-line-or-region t))
(defun sh-switch-to-process-buffer ()
  (interactive)
  (pop-to-buffer (process-buffer (get-process "shell")) t))

(define-key sh-mode-map [(control ?j)] 'sh-send-line-or-region-and-step)
(define-key sh-mode-map [(control ?c) (control ?z)] 'sh-switch-to-process-buffer)

Enjoy.