Credit card fraud is a major problem. I've been a victim myself. What could you carry to prevent it? In short, your phone. AT&T just launched a pilot program that enables companies to verify where you are by tracking you through your smartphone.

If your card number is being used in Illinois but the credit card company instantly sees that you, the authorized card holder, has his smartphone in another part of the country, it's instantly flagged. You'd have to opt in to this, so don't worry about big brother. Read more about it here.