(defun fill-sentence ()
(interactive)
(save-excursion
(forward-char)
(forward-sentence -1)
(indent-relative t)
(let ((beg (point)))
(forward-sentence)
(fill-region-as-paragraph beg (point)))))
(global-set-key "\ej" 'fill-sentence)
Code courtesy of Joe Fineman, with an improvement by Christopher L. Conway.
