Citi offers Price Rewind as a free feature on its personal cards like the:

Citi Prestige® Card
Citi ThankYou® Premier Card
Citi ThankYou® Preferred Card
Citi® Hilton HHonors™ Reserve Card, 
Citi® Hilton HHonors™ Visa Signature® Card
Citi® / AAdvantage® Platinum Select® MasterCard®
Citi® Double Cash Card – 18 month BT offer
Citi® / AAdvantage® Executive World Elite™ MasterCard®

It's not a highly publicized benefit, but it can save you a lot of money each year, as proven by our reader success stories in this post.

Basically you register purchases online and if the price drops within 60 days of the