Well, we know he's not doing this for the extra cash: Friends millionaire Matthew Perry will appear in a special two-hour episode of Fox's Ally McBeal on April 15. Perry will play "a cocky, successful and opinionated attorney who wreaks havoc on Ally's personal and professional life," Fox says. That same episode, Christina Ricci will kick off a four-episode arc as a brilliant, young legal prot&#233g&#233.