I have posted about it once before, in my best friend's wedding i could hear a very good sounding choir. In tune, with good voices and all. Seemed like 4 persons singing.
I thought to myself "ok, this is going to cost him money" and then i realized that while i could HEAR the persons singing, i couldn't actually SEE where they were located.
looking more closely, I spotted the right "chanter" (everyone who's been in a Greek orthodox church will know what I am talking about), singing and touching "something" below his songbook, (this something was under a cloth, hidden from plain view)

I don't know what it was, it had a 3 or 4 octave keyboard (probably little keys). the guy was simply pressing keys and singing at the same time, and beautiful harmonies were produced.
I was amazed.

if that VP roland can do such things, it might be enough reason to buy it so i can see the faces my father will meake when he hears what it can do (he chants sometimes at our church)