Why would people ever want a referral system in Cricket, like Tennis? The world now has PDA devices and wireless technology. If the Umpire needs information, as to whether the ball pitched in line or how high it struck the batsman, they can be made available real time. Almost.
If at all one needs the drama of a referral — use it for snicko. More fun and, the batsman has a personal reputation at stake when he is seeking it.