It might sound silly, but whenever you see a store that has 1-click shopping, they're probably paying Amazon some licensing fees. Amazon was granted a patent for the technique in September of 1999. They also own the trademark of "1-Click." The patent covers a technique through which a store allows a user to complete an online purchase without having to use shopping cart software, and also without inputting billing and shipping information.
Apple is one of the few licensors of this patent. They added 1-Click to their Apple Computer store and then later added it to iTunes and iPhoto. In 1999, Amazon sued Barnes & Noble because of their Express Lane service, which was similar to 1-click shopping. B&N thought they had designed a way to get around the patent, but they still settled out of court.