Quality, B-list film directors like John Dahl and Brad Anderson have been directing episodes of some of my favorite genre shows. Dahl directed Battlestar Galactica's "The Oath," as well as episodes of Dexter, Californication, True Blood, Life, and United States of Tara. Anderson directed two of the best episodes of Fringe, "In Which We Meet Mr. Jones" and "The Transformation."
Anyone notice any other film directors dabbling in TV? Masters of Horror doesn't count.