Just a heads up. In the latest version of slime (slime.el), the function slime-define-key has been deleted.  You can get around this by defining it.  I added the following to js-expander.el.
note: slime-prefix-key has also been deleted.

(defun* slime-define-key (key command &key prefixed inferior)
  (when prefixed
    (setq key (concat "\C-c" key)))
  (define-key slime-mode-map key command))

andy peterson