Countdown to 2011 in Emacs.

countdown.el

(require 'deferred)
(require 'popup)

(defvar countdown-started nil)
(defvar countdown-wait 1000)
(defstruct countdown-tip buffer tip)

(defun countdown-start ()
  "Start countdown to 2011."
  (interactive)
  (if countdown-started
      (message "countdown already started.")
    (setq countdown-started t)
    (countdown-loop)))

(defun countdown-stop ()
  (interactive)
  (setq countdown-started nil))

(defun countdown-loop (&optional tip)
  (when tip
    (countdown-delete-tip tip))
  (when countdown-started
    (lexical-let ((newtip (countdown-show-tip)))
      (deferred:nextc (deferred:wait countdown-wait)
	(lambda (x)
	  (countdown-loop newtip))))))

(defun countdown-show-tip ()
  (unless (minibufferp)
    (ignore-errors
      (make-countdown-tip 
       :buffer (current-buffer)
       :tip (popup-tip
	     (number-to-string
	      (ceiling (time-to-seconds (time-subtract (encode-time 0 0 0 1 1 2011) (current-time)))))
	     :nowait t)))))

(defun countdown-delete-tip (tip)
  (save-excursion
    (when (buffer-live-p (countdown-tip-buffer tip))
      (set-buffer (countdown-tip-buffer tip))
      (popup-delete (countdown-tip-tip tip)))))