BARCELONA, SPAIN - MARCH 2: The Amazon ads logo, the advertising solutions service formerly known as AMD or Amazon Marketing Services, during the Mobile World Congress 2023 on March 2, 2023, in Barcelona, Spain. (Photo by Joan Cros/NurPhoto via Getty Images)Amazon has turned into an online ad juggernaut in recent years, with brands paying big bucks for premium placement on the retailer's websites. Now, Amazon is letting other sites use its ad technology for their own stores.The new offering, called Amazon R ...