Zooey Deschanel and Joseph Gordon-Levitt singing What Are You Doing New Years Eve?… with ukeleles, no less.
Oh, wait. He has a full sized guitar. My bad.
What you may not know about JGL is his involvement with hitRECord (http://www.hitrecord.org/) — a site dedicated to remixing, collaborating & creating content… and then ( *GASP* ) sharing in the profits.