YouTube

7) YouTube

Leave it to the Web's top ad company to produce one of the few bright spots in ad-supported music.

YouTube eclipsed MTV as the premiere music-video hub. The millions of music videos on YouTube, as well as on Vevo--the spinoff the labels created with YouTube's help--have become a music-discovery mecca. As a genre, music videos are the most popular fare on YouTube responsible for hundreds of millions of views. The site also gave us Justin Bieber, for Pete's sake.

As for profits, Google won't disclose, but music industry sources say the four largest record companies are happy with the ad revenue that YouTube produces.