Some time ago, the idea of an instant reference card was bantered about on
the list.  I presented a file called org-help.org.  I have worked on it from
time to time, and it's changed quite a bit.  My most recent idea is to have
it available on a keystroke, completely folded, and each line would
instantly display some of the most commonly used keys for that topic, then
by opening that headline, a tree would be revealed with more detailed
keybindings.  I've played with it, and it's helpful, and I'll make it
available RSN, hoping others will find ways to make it more useful.  My
final touch would be to incorporate a link for each topic to the relevant
topics in the org-mode info manual.  What's missing is the convenience of
info mode, of being able to stuff it away with "q" and call it up again at
the same point.  That would be more convenient.  I'm unable to go forth on
that part of the quest, because I haven't gotten my head around texinfo
(yet?).

Meanwhile, I remembered a little help popup I made to remember all my
keybindings, long years ago.  Here's a quick popup to get a transient
display of some keybindings above the current line.  I didn't understand how
to wire it into org-mode-map's keybindings, so I bound it, for now, to
\C-cp.  The beauty of this gem is to be able to type the keys right away,
and they work.

Please feel free to improve it.  Maybe another two or three of these would
provide a person with his own frequently used keys.

;;;;;; org-popup-help
;;----------------
;; Org Popup Help
;;----------------------
(defun org-popup-help ()
  "Inserts a reminder of my org keybindings momentarily
above the current line, until the next keystroke."
  (interactive)
  (save-excursion
    (momentary-string-display
     org-keys (save-excursion (beginning-of-line) (point))
     nil "Type SPC or any command to erase help.")))                      ;;

(defvar org-keys
  (concat "   |
\n"
          "   |
\n"
;;;
      "  | Visibility Cycling               TAB    C-i \n"
      "  | Motion                           C-c C-n/p / C-c C-f/b / C-c C-u
/ C-c C-j \n"
      "  | Structure Editing                M-RET  /   M-L/R  /  M-S-L/R \n"
      "  | Sorting                          C-c ^ \n"
      "  | Converting to headlines/removing stars     C-c * \n"
      "  | Checkboxes                       M-S-RET\n"
      "  | Archiving [manual]               C-c C-x a \n"
      "  | Filtering and Sparse Trees       C-c / \n"
      "  | Links                            C-c l    /    C-c C-l \n"
      "  | TODO Items                       M-S-RET         C-c C-t \n"
      "  | Tags                             C-c C-q  /  C-c C-c  /  C-c \\n"
      "  | Properties and Column View       C-c C-x p \n"
      "  | Timestamps                       C-c .  /   C-c ! \n"
      "  | *Schedule and Deadline*          C-c C-s  /  C-c C-d\n"
      "  | Clocking time                    C-c C-x C-i  /  C-c C-x C-o \n"
      "  | Relative time clock              C-c C-x .  /  C-c C-x - \n"
      "  | Exporting and Publishing         C-c C-e \n"
      "  | Attachments Dispatcher Commands:  C-c C-a \n"
)
  "*String displayed above current line by \\org-popup-help].")

;(define-key org-mode-map "p" 'org-popup-help)
(global-set-key "\C-cp" 'org-popup-help)
;;;;;;;;;;;;;END org-popup-help.

I'll provide it as a file as well, in case the tabs/spaces get blown away in
the mail.

Alan
-- 
Alan Davis

It is undesirable to believe a proposition when
there is no ground whatsoever for supposing it is true.
    ---- Bertrand Russell
They are ill discoverers that think there is no land, when they can see
nothing but sea.
    ----   Sir Francis Bacon