mtucker-mark-comment.el

(defun mtucker-mark-comment (&optional pos)
  (interactive "d")
  (let ((initial pos)
        (syntax (syntax-ppss pos)))
    (if (nth 4 syntax)
        (progn
          (push-mark (nth 8 syntax) nil t)
          (while (nth 4 syntax)
            (forward-char)
            (setq syntax (syntax-ppss (point)))))
      (message "Not in a comment."))))