I've noticed of late that cashiers will ask to see my card after I've swiped it at the register. But they don't bother to check the signature. What they do is key in the CVV code. The CVV is three digits printed on the back of the card, except for American Express, which prints four digits on the front of the card.
The CVV is not contained in the swipe data. Thus, a card made by recording stolen swipe data on a dead card will not work at, say, Staples, where they enter the CVV, but will work at a grocery store, where they typically don't. Also, I've noticed some gas pumps now ask you to enter your billing zip, a measure which also defeats cards made from stolen swipes.
I read somewhere that total fraud volume amounts to five or ten basis points. It's a big number, but proportionally, it's tiny. You may recall during the 2012 election that Newt proposed out-sourcing immigration security to the card companies.
Never let anyone see the CVV, just the signature. Cover it with your finger.
I honestly don't know of any POS system that asks for the CVV code. Typically, when any numbers are keyed in, it is the last four digits of the card, to prevent re-encoded credit card fraud. As for gas stations, if you show them it is a gift card (hence why they've switched to them), they will waive the zip code requirement, or not require it at all if you pay inside instead of at the pump.
Fraud, though, is a tiny number overall mostly because credit card companies tend to try to enforce investigations into the crime. Vs fraud in insurance claims which dwarfs credit card fraud by at least two orders of magnitude.