In April, A.G. Lafley, the chairman and CEO of Procter & Gamble (NYSE:PG), and Ram Charan, adviser to such business leaders as Jack Welch and Robert Nardelli, published an insider's guide to innovation at P&G and other top corporations. The Game-Changer: How You Can Drive Revenue and Profit Growth With Innovation argues that innovation -- like learning -- must be continuous and pursued at all levels of the organization. The book describes dozens of mechanisms for keeping the idea pipeline full, such as P&G's customer-immersion programs, which send employees to live in consumers' homes, and innovation "hot zones," facilities where product teams spend weeks on creative exercises.