I played Rock Band 2 for the first time a little while ago (at Notacon).

One thing I enjoyed about it was getting real-time feedback about my singing. I think it'd be neat to have something like that to run alongside my usual music, so that I can sing to random stuff in my music collection and know when I'm hitting the notes.

Is there something like this for PC - ideally for OSX, and ideally that can just operate on arbitrary songs?

I don't really care if it's game-like (though that's neat too); I just want it for the singing feedback. And I have no need for pitch correction - ideally what I'd see is just the pitches of the notes in the music and (on the same scale, differently displayed) of the live microphone.

I tried to STFW but got no salient hits. :-/

Thanks!