Pandora did. http://www.techcrunch.com/2009/01/20/pandora-radio-starts-serving-audio-ads/ http://www.techcrunch.com/2009/01/20/pandora-radio-starts-se... (My a

Pandora did. http://www.techcrunch.com/2009/01/20/pandora-radio-starts-serving-audio-ads/ http://www.techcrunch.com/2009/01/20/pandora-radio-starts-se... (My apologies for TechCrunch, but it was the first result)