Where can I find legal peer-to-peer music software?
Stating the obvious, I know, but peer-to-peer (P2P) software is not illegal — it's what you share with others that makes the whole deal legal or illegal.
In other words, you can use any P2P software and if the files you share are legal, then you're fine.
Of course, your real question is whether there's a P2P service that actually has legal music files on it.
Fortunately, there is. It's called Qtrax.
It's still in the beta phase and they're busy ironing out some problems, but the important thing is that — according to them — the music files that you download from them are free and, more importantly, legal.
The artists of the songs and the record labels apparently get compensation for the songs you download through ads sold on the site.
It sounds too good to be true and time will tell whether the record labels continue to support them, but for now, it's time to find that favourite song of yours!