Agree w/"Kumbaya" and "Michael, Row the Boat Ashore."

How about "Wimoweh," "This Land is Your Land," "Dem Bones," "Skip to My Lou?" There are a bunch that have been done so much that its now 'uncool' to sing them. I'm usually immune to this, as I love to sing the old standards, but I have to admit that "Mary Ellen Carter" (which i once loved) is rapidly becoming unendurable.