I needed to write 31 thank-you-for-attending-my-send-off-party e-mail
messages. Instead of having a generic letter that I'd send to lots of
people all listed in To: or Bcc:, I decided to personalize it a bit by
including their nicknames, two-year goals, and a personal message I'd
add to each letter in different places.

Fortunately, my mail client was up to the task. One of the benefits of
having both your contact information and your mail client in an
easily-programmable environment is that you can hack together a quick
program to do exactly what you want.

I had typed everyone's two-year-plans into my contact information
manager's Notes field following a special format. It was the work of a
few minutes to record and run a macro that extracted the data and
created a signature for each person who attended my send-off party.

I then wrote a couple of short functions that looped over the
currently displayed contact records and drafted messages for each of
them following a template.

This resulted in 31 drafts I could edit and send without hassles. Much
fun!

For future reference (and for the handful of Emacs geeks or learners
in the audience), here's the code I used to make it all happen:

(defun sacha/bbdb-send-form-mail (bbdb-record &optional subject template)
  "Compose a form message to the people indicated by the current BBDB record(s)."
  (interactive (list (if (bbdb-do-all-records-p)
                         (mapcar 'car bbdb-records)
                       (bbdb-current-record))
                     (read-string "Subject: ")
                     (read-string "Template (): ")))
  (if (consp bbdb-record)
      (let ((records bbdb-record))
        (while records
          (sacha/bbdb-send-form-mail-1 (car records) subject template)
          (setq records (cdr records))))
    (sacha/bbdb-send-form-mail-1 bbdb-record subject template)))

(defun sacha/bbdb-send-form-mail-1  (bbdb-record &optional subject template)
  "Compose a form message for one person."
    (if bbdb-inside-electric-display
      (bbdb-electric-throw-to-execute
       (list 'sacha/bbdb-send-form-mail bbdb-record subject)))
  ;; else...
  (cond ((null bbdb-record) (error "record unexists"))
        ((null (bbdb-record-net bbdb-record))
         (message "%s record unhas a network addresses." (or (bbdb-record-name bbdb-record) "Unknown")))
        (t (bbdb-send-mail-internal (bbdb-dwim-net-address bbdb-record)
                                    subject (list bbdb-record))
           (goto-char (point-min))
           (when (re-search-forward "--text follows this line--" nil t)
             (forward-line 1)
             (insert template)
             (goto-char (point-min))
             (while (search-forward "" nil t)
               (replace-match (or (bbdb-record-getprop bbdb-record 'nick)
                                  (bbdb-record-name bbdb-record))
                              t t))
             (when (bbdb-record-getprop bbdb-record 'signature)
               (goto-char (point-max))
               (insert "\n")
               (let ((p (point)))
                 (insert (bbdb-record-getprop bbdb-record 'signature))
                 (fill-region-as-paragraph p (point))))
             (goto-char (point-min))
             (if (re-search-forward "^Subject: $" nil t) (end-of-line))))))

I used M-x local-set-key to bind sacha/bbdb-send-form-mail to M. * M
then applies the function to all displayed records.
../emacs/miniedit.el makes it easy to edit long strings in the
minibuffer, and that made the template much easier to write.

Emacs totally rocks. Nothing else has ever given me this much power.