SecureID has had a car with a 4 to 6 digit pin that changes every minute. Why not just use that technology in cards you wish to protect? Maybe change the delta-T to every 5 minutes and make the code okay to +/- several codes, just in case the code's time sync gets out of sync.

Pros:
- No change to ATMs other than a small software change
- Simple to use and understand

Cons:
- Credit/debit cards are more expensive to manufacture because they have LCD display and logic to include

Make this an optional service: those who want more security can elect to have this; those that don't care can continue on as they do today.