It's that time of year when institutions of higher learning heartlessly eject their seniors into the real world! Princeton grads were treated to the best speech of the season; Stephen Colbert delivered a zinger-filled address (above) in which he wisely reminded grads that "no one will ever, ever want to hear you sing a capella" outside college. How true. But plenty of other colleges tapped A through Z-list celebs to brace their soon-to-be-discharged students for entry into the workforce.