kJams

Not really
Spotify allows you to have a collaborative playlist and or share playlist with other users
I sure there is a way you can pull from that info.

Sync with spotify?
If there were a way were you can connect to users spotify account to their karaoke playlist.
IE: I have a playlist on my spotify that are my karaoke songs, how awesome would it be if i can
A: see what songs users want to sing in advance because i can see their songs in their ...

Also noticed that you havent updated the iphone app in 4 years.. maybe this isnt the best program if you arent supporting it any longer.

I just got a new computer and tried to activate my kjams pro and i get this message.
"There was an error with that serial number, Please check the number and try again."
I am on Mavericks now and new mac book pro retina