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