Four-year-old Kevin White of Richmond, Calif., is enjoying that all-American event, a birthday party at McDonald's. Wearing a Ronald McDonald birthday hat and clutching a fistful of French fries, he gets ready to whisk down the slide in the restaurant's kiddy playground, while his mother Cynthia stands by with envy. "One day I hope that Kevin will appreciate my cooking," she says. "But for now, I can't even compete with a Big Mac and fries."
She may not be able to compete, but a burgeoning number of entrepreneurs think they can. Americans are eating out more than ever, and more than...