Once I factor out the Grateful Dead tunes, here are my top five tracks from my last.fm charts for 2008:
Greg Brown, Canned Goods
World Saxophone Quartet, Hattie Wall
Miles Davis, Bitches Brew
Greg Brown, If I Had Known
Greg Brown, Cold and Dark and Wet
The next highest one that is not by one of those guys/bands is Dylan's "Stuck Inside of Mobile with the Memphis Blues Again," followed by Chris Smither's "Leave the Light On."
An old Deadhead who loves jazz and folk, that's me. :-)