Joni Mitchell has always been a favorite of mine. Her work has the same relevance now that it did when she wrote them in her 20s, and the subsequent years have only brought more poignance to her lyrics. Case in point: listen to her sing "Both Sides Now" at the Tribute to Joni Mitchell in 2000:

So here's your challenge tonight: Your challenge--if you choose to accept it--is to link a classic song that you feel gains more resonance or poignancy from the passage of time.