One of the benefits of signing up with a service like Paypal is that you can go to the backend and remove the running weekly/monthly charges from your profile. However the same cannot be said with a credit card signup as it makes it more difficult to unsubscribe.
Well .If you ever had to sign up for a product or service with a valid credit card but were afraid to be billed for ever then this could be a perfect remedy. http://www.getcreditcardnumbers.com/ generates a valid credit card number that you can use across the web for testing your ecommerce site or signing up to sites that insist or credit cards. A useful service to sign up for stuff you just want to try out before buying