Brand tone (how something feels and the impression it leaves) is one of the most important things that separate good marketing from great marketing... And it's surprisingly difficult to articulate and manage consistently over time.
Apple has been terrific at this. Most recently, Intel and agency Venables Bell + Partners have also created a campaign that has a wonderful, smart but playful tone... Enjoyable to watch and pay attention to.
And then, of course, from earlier this year...