SoulSeek is a good old music file sharing
Quick overview
Soulseek is a file sharing program for the Soulseek p2p (peer-to-peer) network that is mostly used to exchange music although users can share all kinds of files. The Soulseek network uses a proprietary file sharing protocol using a central server.

Pluses
- Soulseek is a spyware-free file sharing client.
- Users can download whole folders instead of just single files.
- Soulseek allows its users to create chat rooms to discuss various types of files shared over the network. Chat rooms are dedicated to geographical regions or musical styles. Searching for files in a room is faster than a global network search.
- User can increase the rate of downloading files from other users by donating money to administrators.
Minuses
- Using the central server. It used to be the reason for network crashes due to CPU overloading.
- Bad documentation.
Unofficial Soulseek clients
SoulseeX – client for Macintosh
PySoulSeek or Pyslsk - Linux client
MySeek - Linux client
mlDonkey
OctoFind
Related Software: Limewire