Until ukbobboy01 returns, there were some posts on the forum which discussed this but they've temporarily gone missing. What I can tell you is that there are some out there being shared. Search for cdg or cd+g. I had good results when searching these terms some time back. Other Karaoke formats include: .MID+.TXK, .MID, .CRT, and .ST3
A little more info here http://www.gnutellaforums.com/showth...893#post122893
BTW cdg is the extension so you might want to search .cdg