For centuries people would use personal calling cards to announce their visits, or leave when their friends were out. A new trend right now is to create personal business cards to use along with your resume that include work history related information.
Don't waste 50% of the business card by leaving the back of the card blank. I had a manager once that insisted the back of a business card should be blank so you can write information on it, but most of the time you are not going to do this. Why waste all that real estate on your card?
With prices for double sided business cards being only a few pennies more, it doesn't make sense not to use both sides. You could use the back as a sort of bullet point resume with your skills or special accomplishments highlighted. And the front can contain contact information.
Having a professional looking resume along with a great looking personal business card will be the edge you need to land that great new job!