Christopher Johnson is a branding consultant with a PhD in linguistics. His book, Microstyle: The Art of Writing Little is filled with examples of great (and less-than-great) brand names and taglines.
He explains why certain taglines, ad campaigns, and brand names work, and why others fall flat. Often it’s simply because of how they sound. Other times it’s because of the clever use of metaphor. One of his examples is Maytag, which for many years used the metaphor of “The Lonely Repairman” to communicate an important but mundane product benefit – reliability.
Here is a review from the New York Times, also.