PayPal is set to offer a new service dubbed “PayPal Secure Card” beginning tomorrow. The service, offered through a web browser plug-in, will allow users to generate a unique one-use MasterCard number to use on sites that don’t accept Paypal. According to the Reuters article:

By residing on the PayPal user’s computer, Secure Card can detect when users visit e-commerce sites. The software then automatically fills in their stored financial information, requiring just a few more clicks to authorize a transaction.

PayPal stores no details on the local computer for security reasons. Instead, it logs Secure Card activity in the user’s account on central computers for safety and record-keeping.

At this point, there has been no mention of whether you will eventually be able to earn rewards on these purchases. There are, however, a couple of immediately recognizable benefits for consumers: 1) credit card access for those without a credit card, 2) virtual credit card numbers for those who don’t have a credit card with this ability (eg, Chase, Amex).