smart-tab.el

(global-set-key [(tab)] 'smart-tab)
(defun smart-tab ()
  "This smart tab is minibuffer compliant: it acts as usual in
    the minibuffer. Else, if mark is active, indents region. Else if
    point is at the end of a symbol, expands it. Else indents the
    current line."
  (interactive)
  (if (minibufferp)
      (unless (minibuffer-complete)
        (dabbrev-expand nil))
    (if mark-active
        (indent-region (region-beginning)
                       (region-end))
      (if (looking-at "\\_>")
          (dabbrev-expand nil)
        (indent-for-tab-command)))))