I've always done business cards the "normal" way, which is to print everything on one side. But when I walked a block from my office to the neighborhood print shop, I discovered exactly how much things have changed. The place is Impress Digital Printing Solutions, and their setup is really cool. The default setting on their equipment is 4-color, 2-sided printing. The second side is at no additional charge. So I'm printing my Mouzon Design cards and my New Urban Guild cards with Original Green backs, since the Original Green idea underlies almost everything we do. One-sided cards all look alike when a stack of them are turned over.
Two-sided ones, OTOH, never get lost among the white-backs. There's another idea here, too. All of these things have been available for a century or more: 2-sided, 4-color card printing. But most people never even considered it. Why? Because printers used to charge per press run, so 2-side, 4-color equals 8 passes through the press. But the people that made this machine apparently said "what would a machine look like that printed the best cards, postcards, etc.?" And so they made the good stuff the default setting. There's an obvious Mac/Windows comparison here. In any case, look me up... I'll have some with me.