(following-char) (preceding-char)
(char-after)
(skip-chars-forward)

(bury-buffer)
(browser-url)

(expand-file-name)
(file-name-as-directory)                ; append a slash
(directory-file-name)                   ; remove final slash
(file-name-directory)                   ; directory component
(file-name-nondirectory)                ; filename
(directory-files)                       ; get files list in a directory

emacs -batch -f batch-byte-compile thefile.el

(defun quote-range (ch &optional pair)
  (if (region-active-p)
      (let ((begin (region-beginning))
            (end (+ (region-end) (length ch))))
        (goto-char begin)
        (insert ch)
        (goto-char end)
        (insert (or pair ch)))
    (insert ch)))
(global-set-key "'" '(lambda () (interactive) (quote-range "'")))
(global-set-key "\"" '(lambda () (interactive) (quote-range "\"")))
(global-set-key "(" '(lambda () (interactive) (quote-range "(" ")")))

;; Compile your .emacs
(defun autocompile nil
  "compile itself if ~/.emacs"
  (interactive)
  (require 'bytecomp)
  (let ((dotemacs (expand-file-name "~/.emacs")))
    (if (string= (buffer-file-name) (file-chase-links dotemacs))
      (byte-compile-file dotemacs))))
(add-hook 'after-save-hook 'autocompile)

;; Compile2
(require 'bytecomp)
(setq compiled-init-file (byte-compile-dest-file user-init-file))
(if (or (not (file-exists-p compiled-init-file))
        (file-newer-than-file-p user-init-file compiled-init-file)
        (equal (nth 4 (file-attributes user-init-file)) (list 0 0)))
    (load user-init-file)
  (load compiled-init-file))
(add-hook 'kill-emacs-hook
          '(lambda ()
             (if (file-newer-than-file-p user-init-file compiled-init-file)
                           (byte-compile-file user-init-file))))

;; http://www.emacswiki.org/emacs/OptimizingEmacsStartup
;; autoload & eval-after-load