American Express just sent out this offer whereas if you spend in 8 different places, you will get a $30 prepaid card. This is a targeted offer, but there is no harm in signing up even if you didn’t get an email. Before you sign up, read their FAQ page for more info.
According the terms:
The American Express “On the Card” Program (“Program” ) starts at 12:00 AM Eastern Standard Time (“EST”) on 10/15/07 and ends at 11:59 EST on 12/09/07. Available to legal residents of the 50 United States or the District of Columbia who are holders in good standing of an American Express® Card issued in the U.S. by American Express who have received an e-mail offer regarding this Program. This promotion is not open to individuals who have an American Express Card issued by a third-party bank issuer. In order to qualify, eligible Cardmembers must register and receive a confirmation e-mail indicating their acceptance into the Program. Offer is subject to availability and is limited to the first 12,000 registrants. To register, participants will need to enter a valid American Express Card number. Only one registration will be allowed per Cardmember account — if a Cardmember has multiple American Express Cards, the Cardmember can only participate once with one Card. Limit one American Express® -branded prepaid card per Cardmember. Offer is subject to change without notice. Offer expires 12/09/07.
In order to be eligible for a prepaid card, you must register at amexnetwork.com/onthecard, where you will be asked to enter your American Express Card number, expiration date, and e-mail address and select 8 participating merchants. Once you have confirmed your 8 merchant selections, you cannot change your selections. You must complete one transaction at each of the 8 merchants that you select in order to receive a prepaid card. Multiple transactions at the same merchant will not be counted toward your total of 8 purchases. You will not be credited for a transaction if you shop at other participating merchants that you did not initially select