This is the businesscard I did for the graphical manual for school. A slick nice look I wanted for it.

My material for this featured a lot of light gradients, and I used that on both sides here. A light grey like on everything else on the front, but also a light orange on the filled color on the back. The only other place I used that was on the cover of the manual.

I think the back of the businesscard is important and that it should send the right message. If it's blank I can understand, then it is economical why it is. But you shouldn't just put the logo there, bam boom. Create something interesting, because if a person looks at it, you want him or her to turn the card around and look at the side with all the information. If it's just a logo they know what it is.
To try it yourself. Think of this scenario: You walk into a room and see the card on the table with the backside up. Would you turn it and look at the other side?

Orange text on the front says "e-mail" and "phone" but you probably figured that out.