i was wondering about the same thing dan was.  I already took a bunch of covers that I redid myself and put them on the internet.  However, they are all classical covers and I don't think the Bach family is try to come after me.  But let's say I did this with modern music.  No one has ever paid for a copy of the songs, yet I put my name on them and list it as a cover of the original artist.  Anyone that wants to hear it can download at will.  Is there anyway the artists could prevent me from doing this?  You might say no because I am not making any money off of it.  But what if I did them so well that I became famous?  Because of the cover songs, I could make a great deal off of my first original release.  Would I owe anyone?

Now, could the original artist sell my version of his song without my permission??