J. Walter Thompson was among the first agencies to employ writers and artists to create interesting advertisements for their clients, replacing the standard ads created by in-house departments. It was also the first agency to provide a wide range of advertising services to clients, including copy, layout, package design, trademark development and rudimentary, market research. Many of these methods can be seen in notable work that the agency has produced, including work for Kraft Cheese that resulted in the creation of the grilled-cheese sandwich, a campaign for Swift & Co. that added measurement marks to sticks of butter, the Toys "R" Us Kid slogan and jingle, De Beers diamond ads ("A Diamond is Forever") and the "I wish I were an Oscar Mayer Weiner" campaign.