Experiencing music as a social activity used to mean going to a concert, or maybe a party. And to learn about new music or artists in the days of yore, you had radio, record shops, or the much-fabled mix tape .
But in the Internet and iPod age, listening to music became a more solitary experience--the earbuds, the personal playlists, the Pandora stations made just for you.
Turntable.fm  founder and CEO Billy Chasen wants to reverse that trend and bring music lovers together again, online. Turntable is one of the first truly social music networks, where people are listening and interacting online with others at the same time.
Users can play and share music from their personal collections or Turntable's library, taking turns as DJs in rooms themed by era or genre; you can join friends' rooms by logging in through Facebook. DJ avatars man turntables at the front of a room, while a crowd watches and listens, ready to vote up their favorite songs and reward DJs they like with points. Those points can be exchanged for upgraded avatars. The result is that a Turntable event not only sounds like a party, it looks like one. The social elements like the DJ-room chat function and voting, combined with game elements like amassing points and fans, make it hopelessly addictive.
"The idea of Turntable is to take the offline experience of listening to music with friends and bring that online," says Chasen. "Instead of having that experience where everyone just has their headphones in and all you do is listen to your own music, you're sharing music with everyone else and learning and discovering new songs."
Before Turntable, Chasen--who has quite an artistic bent --cofounded Betaworks , where he created real-time analytics service Chartbeat , and firef.ly, a chat service. Turntable recently raised $7 million  in a round of funding led by Union Square Ventures, with Fred Wilson coming on as a board member, and launched its iPhone app  in September. Turntable currently has about 725,000 users, who stream anywhere from 500,000 to a million songs a day.
And as it turns out, all those people meeting up online has led to some real-world interaction, as well.
"One of the coolest things to happen with Turntable is that people have been forming these parties offline and using Turntable to power them," Chasen says. "So the party is this hybrid offline/online experience, where there are physical people in a room, listening to a Turntable room. Some of the DJs might be in the room, and other people might be DJing from the Internet."
Sounds like a good time.