Martin Cracauer wrote some code which emulates the SELECT key from a Symbolics Lisp machine. EdwardOConnor adapted that some, and here’s my adaptation of that along with some keybindings that I commonly use.

;; stesla-f8-prefix-map is a sparse keymap defined earlier in my .emacs
;;(defvar stesla-select-prefix-map stesla-f8-prefix-map)

;; updated 7/30/07 now works with 22.1
(define-prefix-command 'stesla-select-prefix-map)
(global-set-key [f8] stesla-select-prefix-map)

(global-set-key [menu] stesla-select-prefix-map)
(global-set-key [apps] stesla-select-prefix-map)

(defun stesla-display-select-bindings ()
  (describe-bindings [f8]))

(define-key stesla-select-prefix-map "?" 'stesla-display-select-bindings)

(defmacro stesla-define-select-key (fname-base key &optional buf-form else-form)
  "Define a select-key function FNAME-BASE bound on KEY.

If provided, BUF-FORM should be a form which will attempt to return
a buffer to switch to.  If it returns nil, ELSE-FORM is evaluated."
  (let ((fname (intern (concat "stesla-select-" (symbol-name fname-base)))))
       (defun ,fname (arg)
         (interactive "P")
         (let ((buf ,buf-form))
           (if buf
               (switch-to-buffer buf)
       (define-key stesla-select-prefix-map ,key ',fname))))

(put 'stesla-define-select-key 'lisp-indent-function 2)

(defmacro stesla-define-select-key-class (fname-base key extension &optional default-dir)
  `(stesla-define-select-key ,(intern (concat (symbol-name fname-base) "-file")) ,key
     (let ((buffers (buffer-list))
           (buffer t))
       (while (and buffers
                   (listp buffers))
         (setq buffer (car buffers))
         (setq buffers (cdr buffers))
         (if (string-match ,extension (buffer-name buffer))
             (setq buffers nil)
           (setq buffer nil)))
      (read-file-name ,(concat "Find " (symbol-name fname-base) " file: ")

;; These are the file types I use at least semi-regularly.

(stesla-define-select-key-class C          "c" "\\.c$")
(stesla-define-select-key-class Emacs-Lisp "e" "\\.el$"     "~/.elisp/")
(stesla-define-select-key-class HTML       "h" "\\.s?html$" "~/www/")
(stesla-define-select-key-class Lisp       "l" "\\.\\(lisp\\|lsp\\)$")
(stesla-define-select-key-class LaTeX      "t" "\\.tex$")
(stesla-define-select-key-class Makefile   "M" "\\(GNU\\)?[Mm]akefile")
(stesla-define-select-key-class m4         "4" "\\.m4$")

;; For easy access to a few commonly accessed files/buffers.

(stesla-define-select-key dotemacs-file "."
  (find-buffer-visiting stesla-dotemacs-file)
  (find-file stesla-dotemacs-file))

(stesla-define-select-key home-directory "~"
  (find-buffer-visiting "~")
  (dired "~"))
;; That ~ key is impossible to type...
(define-key stesla-select-prefix-map "`" 'stesla-select-home-directory)

(stesla-define-select-key info "i"
  (find-buffer-visiting "*info*")

(stesla-define-select-key shell "!"
  (find-buffer-visiting "*eshell*")

(stesla-define-select-key gnus "g"

I’ve updated this module to be a bit more modern: you can repeat the selection key to cycle through buffers matching the same type. The newer version is at Lisp:selectkey.el. – JohnWiegley