...and a very long exhaust hose so you don't kill yourself with the carbon monoxide?

Unless you perform a task that moves the mark before you jump back, of course :D

The following functions will save the current location to a register when going to the beginning of the file or end of file with M-. You can then go back to the last place you were with C-x r j 1 ;;; a trick from ispell... ;;; Let ?1 do the right thing when compiled.
(defun lrd-int-char (char)
    (cond
      ((and (fboundp 'characterp) (characterp char)) char)
      ((and (fboundp 'int-char) (integerp char)) (int-char char))
      ((integerp char) char)
      (t (error "arg is not an int or a character")))) ;;; ;;; misc. advice stuff

(defadvice beginning-of-buffer
    (before bob-register first () activate)
    "When going to beginning of buffer, save point in register 1"
    (point-to-register (lrd-int-char ?1)))

(defadvice end-of-buffer
    (before eob-register first () activate)
    "When going to end of buffer, save point in register 1"
    (point-to-register (lrd-int-char ?1)))