The basic form of interaction with the service is via "thumbs up" or "thumbs down" icon the user clicks on a particular song. If I click one way or the other, I fine-tune my music listening experience (a "thumbs down" click means that I will not hear that song again, for example). Now get this -- Pandora just recorded its 10 BILLIONTH thumb! THAT is impressive.
So, while I previously have questioned Pandora's actual profitability, no one can question its ubiquity. Virtually everyone I know uses it. And, as you may recall, Pandora recently filed for a $100 million IPO that is expected to value the company at nearly $1 billion.
That kind of cash certainly can buy a lot more thumbs ...