I guess I'm looking for karaoke in reverse. I want the vocals, not the music.
I have recently started a 2 for 1 tribute band covering The Cure and Depeche Mode. It would be very handy having the vocal tracks if our singer is unavailable for rehearsal.
There is some software on the Internet that would help you with this, but it depends on the channel in which is the voice registered. In the most cases, there's no problem, but there can be mp3's in which the voice is registered on the same channel with the instruments and there's no chance...