The free ares download site is a popular alternative to Apple Itunes that has attracted millions of users from around the world.  It runs using file sharing software meaning that once you are a member you can upload your music files for sharing across the network and you can also have access to the files that others have allowed to be shared.  This means that you can search across the music libraries of millions of members to find whatever MP3 files that you want and then download them to your home computer.  With so many users it is almost guaranteed that you will be able to find whatever kind of music you are looking for.