"More important, the tech start-ups that have attracted so much interest from investors have real businesses -- not just eyeballs and clicks," DealBook writes. "Companies like Facebook have fast-growing revenue. Groupon, which has been profitable since June 2009, is on track to take in billions in revenue this year." Since 1999, meanwhile, when 248 million people were online (less than 5% of the world's population), broadband Internet and personal computing have become mainstream. Today, about one in three people are online, or roughly 2 billion users, according to data from Internet World Stats.