Cyrus Massoumi, CEO of ZocDoc, went to this year’s Consumer Electronics Show in Las Vegas to convince investors and others that online health care companies have a business model worth taking seriously. Massoumi appeared on a panel at CES with other consumer electronic brands and Will.i.am of the Black Eyed Peas. ZocDoc provides online referrals to patients seeking health care. Users log in and search for providers who meet their needs. Barry Cohen, a SoHo primary-care physician, said he found the service useful. It gave him access to young, affluent yet often transient patients. He told Crain’s that it took an effort to integrate ZocDoc’s booking into his existing medical records system. Several of his colleagues tried it, but dropped the service when they didn’t get enough patients.