kohit.net is one that I know. But I can't pledge that it would be legal. I agree with others, I don't think that there are anything which would be legal and free. Except those garage bands. I also know a site which is full of those garage bands' legal music but I reckon that there are a language barrier which prevent you to use it (if you still wan't to try, the web site is http://www.mikseri.net).
I've understood that LimeWire is legal but the music isn't. Except if you load something which have put on the list legally.
"Ei oo, ei tuu, ei heru, eikä tipu
Tämä elo on kuin kivinen perunamaa
Ei oo, ei tuu, ei heru, eikä tipu
Sieltä ituisia perunoita aina vaan saan"
Stig - Perunamaa