Some 22 million listeners get their music fix from Pandora, an online radio site that recommends tunes based on user preferences. Real human beings choose songs based on up to 400 musical attributes, and founder Tim Westergren holds public meetings across the country 15 times a year. That kind of high-touch service paid off when 1.7 million listeners besieged Congress to demand repeal of a royalty statute that threatened Pandora's existence. "I've never, ever given up, even when we were in the most depressive bleak times," Westergren said in 2007. Pandora takes in about $25 million a year with a business model that relies on advertising, subscriptions and revenue sharing.