Soulseek is a P2P file sharing system centered around music in particular. It's pretty direct. Unlike a torrent where you'll have multiple seeds for a single source, you're connecting directly to other individuals for the content. It generally operates under the expectation that you're also sharing something, and some users may opt not to allow downloads to people who do not also allow downloads from themselves. The downside to this system is you may need to wait for that person to come online before you can start a download, while with a torrent, other seeders can fill that gap.

It's survived as a pretty big platform for music hoarders to source hard to find material, but it's so dead simple to use and it has a quick and reliable search. Nothing secretive about it, it's basically just another P2P network that has more in common with Napster than the Pirate Bay