You haven't lived until you've heard "Jingle Bells" sung by Tuvan throat-singers accompanying a banjo-fronted jazz-funk band

Makes it a little difficult to sing along to "What Child Is This - Dyngyldai," though.

nobleplatypus pointed out a while back that Fleck does each day in his "Twelve Days of Christmas" in a different key and time signature: the first day is 1/4, the 2nd is 2/4, the 3rd 3/4, etc.. That whole album is unbelievably cool.

The Vince Guaraldi Trio's Charlie Brown album remains definitively Christmas for me, though. I even like "My Little Drum."