Tastebuds.fm

Tastebuds is a dating and social networking website and iOS app that matches people based on their tastes in music.
Overview.
Users can connect with Facebook, Spotify or Last.fm, or enter some of their favorite musical artists to be matched with people who share their musical preferences.
Tastebuds is integrated with popular events service Songkick allowing users to arrange to meet at concerts they're attending.
Messaging is free on the iPhone app but is not free to new website users as of January 2014 but existing users can message anyone.
Tastebuds acquired one if its competitors, moosify in 2014, bringing along approximately 100,000 members with it.