Some random clojure/nrepl emacs lisp that I hacked together today which could be useful.

xxx.el

;(define-key clojure-mode-map (kbd "C-c ;") 'nrepl-insert-balanced-comments)
;(define-key clojure-mode-map (kbd "C-c M-;") 'nrepl-remove-balanced-comments)

; inspired by http://bc.tech.coop/blog/070122.html
; ported from slime/contrib/slime-editing-commands.el
(defun nrepl-insert-reader-comment (prefix)
  "Insert a reader comment (#_) around the s-expression containing the point.
If this command is invoked repeatedly (without any other command
occurring between invocations), the comment progressively moves outward
over enclosing expressions. If invoked with a positive prefix argument,
the s-expression prefix expressions out is enclosed in a set of balanced comments."
  (interactive "*p")
  (save-excursion
    (when (eq last-command this-command)
      (when (search-backward "#_" nil t)
        (delete-char 2)))
    (while (> prefix 0)
      (backward-char 1)
      (cond ((looking-at ")") (incf prefix))
            ((looking-at "(") (decf prefix))))
    (insert "#_")))

(defun nrepl-remove-reader-comment ()
  "Remove a set of balanced comments enclosing point."
  (interactive "*")
  (save-excursion
    (when (search-backward "#_" nil t)
      (delete-char 2))))

;(define-key nrepl-interaction-mode-map (kbd "<f7>") 'nrepl-send-to-repl)
; inspired by http://bc.tech.coop/blog/070424.html 
(defun nrepl-send-to-repl (arg)
  "Send the appropriate forms to the repl to be evaluated."
  (interactive "P")
  (save-excursion
    (cond 
      ;; Region selected - evaluate region
     ((not (equal mark-active nil))
      (copy-region-as-kill (mark) (point)))
      ;; At/before sexp - evaluate next sexp
      ((or (looking-at "\s(")
     (save-excursion
	     (ignore-errors (forward-char 1))
	     (looking-at "\s(")))
       (forward-list 1)
       (let ((end (point))
	     (beg (save-excursion
		    (backward-list 1)
		    (point))))
	 (copy-region-as-kill beg end)))
      ;; At/after sexp - evaluate last sexp
      ((or (looking-at "\s)")
	   (save-excursion
	     (backward-char 1)
	     (looking-at "\s)")))
       (if (looking-at "\s)")
	   (forward-char 1))
       (let ((end (point))
	     (beg (save-excursion
		    (backward-list 1)
		    (point))))
	 (copy-region-as-kill beg end)))
      ;; Default - evaluate enclosing top-level sexp
      (t (progn
	   (while (ignore-errors (progn
				   (backward-up-list)
				   t)))
	   (forward-list 1)
	   (let ((end (point))
		 (beg (save-excursion
			(backward-list 1)
			(point))))
	     (copy-region-as-kill beg end)))))
    (set-buffer nrepl-nrepl-buffer)
    (unless (eq (current-buffer) (window-buffer))
      (pop-to-buffer (current-buffer) t))
    (goto-char (point-max))
    (yank)
    (if arg (progn
	      (nrepl-return)
	      (other-window 1)))))