Ed Keller, co-author of 'The Face-to-Face Book'

Companies around the globe are trying to big up their brands on sites like Facebook and Twitter. The research firm E-marketer says the social media advertising will be worth $10 billion next year. But Ed Keller, Chief Executive of the consulting firm Keller Fay Group, says advertisers should not put all of their eggs into one social media basket. He's also co-author of "The Face-to-Face Book", in which he argues that social media is not the king of the advertising hill.