I often don't watch the sign-off of Colbert. But this past Thursday, I am so glad I did. AMAZING version of "Lean on Me" sung by Colbert, Brian Eno (that night's guest) and Michael Stipe of REM whom Colbert added to his Rock and Roll Shelf of Fame.
This is a link to the video on Colbert Nation for US readers.
This is a link to the video on Comedy Central for Canadian readers.
I've embedded another version of it below, but Viacom pulls these down pretty fast, so it may not be there for very long. But if it's not there, definitely check out the official sites - great trio!