Here's an American classic. The Crucible, the great play by Arthur Miller, premiered in 1953, and it famously used the 1690s Salem Witch Trials to offer a commentary on McCarthyite America. Thanks to LA Theatre Works, you can now listen to the play online. The production stars Stacy Keach, Richard Dreyfuss, Ed Begley, Jr., Joe Spano, and Michael York, among others. And it's directed by Martin Jenkins. You can access it in two mp3s: Hour 1 here and Hour 2 here.

Update: It appears that this program is no longer available online. If you really want a free copy, you do have one good alternative. You can download the performance of The Crucible, as an audio book, if you register for a 30-day free trial of Audible.com. Once the trial is over, you can continue your Audible subscription (as I did), or cancel it, and still keep the audio book. The choice is entirely yours.