Gateway site: https://payments.amazon.com/sdui/sdui/index.htm
Note: Amazon FPS Gateway is only available in the USA
Overview of Amazon Simple Pay
Amazon Simple Pay is a set of basic payment-only products. Using online Amazon Simple Pay forms you can create fully-functional payment buttons, which you then add to your web page. These buttons allow your customers to use their Amazon.com accounts as a payment method for purchasing products and services from you. When customers click one of your Amazon Simple Pay buttons, they begin making a secure payment.
2013.06.28 - version 1.0.1 * Fix bug: Don't use esc_attr function * Upate: Using recommended library of provider 2013.05.28 - version 1.0.0 * First Release