For MP3 files, it's obvious - a p2p filesharing program. If you don't know what that is, it's a program where you can share your media files with everybody on that network so they can download files directly from your computer to theirs. In turn, you can download files from their computers onto yours. That's what p2p (peer to peer) means. So you can download practically any music in the world from these programs all for free. It doesn't cost anything to download the programs themselves and it doesn't cost anything to download files either. The one that I use is called Kazaa Media Desktop, and I think it's the easiest one to use. You can download Kazaa from this site. There are other p2p programs like Morpheus, Grokster, Shareaza, and many more to choose from. You may have heard that these are illegal because it's basically stealing media. Well..... technically I guess it is, and the record companies are trying to sue them. But I think Morpheus and Grokster won some lawsuit, so things are looking up for filesharing things!

If you're looking for any other audio type, I still suggest looking on a p2p program and if you can't find it on one of those then I'm sorry, but you might actually have to go out and buy the song, lol!