It's difficult to find free music that can legally be used in games (I assume that's why you want it?). http://www.modarchive.com has a lot of stuff in MOD format, but the licencing terms are not clear.
Of course, if you just wanted it to listen to, then you don't need to worry about the licencing, since the artists submitting to that site put up their songs so that they will get listened to. =)
http://freeplaymusic.com is another site I've seen; most of the music isn't that good though. At least not the tracks I listened to.
Audacity will convert WAV and MP3 files to OGG. As for MOD files, I don't know of a good one - I just play them as they are in Winamp (and BYOND can play them natively too, since version 3.5). You should be able to find one pretty easily though, there are loads all over the internet.
Of course, if you just wanted it to listen to, then you don't need to worry about the licencing, since the artists submitting to that site put up their songs so that they will get listened to. =)
http://freeplaymusic.com is another site I've seen; most of the music isn't that good though. At least not the tracks I listened to.