Karmin's mega-viral covers of pop and hip-hop hits racked up 178 million YouTube views as of earlier this year, giving them enough juice to sign with a major record label and start actually selling music. Once they scored a hit of their own with "Brokenhearted," the cycle began anew as other users started uploading covers and novelty versions of Karmin's song. One music-business source estimates that acts can make $1,500 per 1 million streams on YouTube this way via advertising. Top stars can make even more by signing up sponsors.
Potential payday: Hundreds of thousands
Downsides: It takes a lot of views to make a little money. And when artists opt to run ads on their YouTube clips, the industry source says they have no input into what type of ads pop up.