FavorAMP - It allows you to search online for people listening to the same music.

It is a FREE Winamp plugin, and search online for the users who are listening to the same artist, or genre! You can enjoy listening to rock, or dance, or techno, or anything you like - and in a click of mouse you find someone loving the same! Once you found somebody, you can send him/her a message, and get an answer with our online instant messaging system!