One of my favorite discoveries since I began studying objectivism is historian Dr. Eric Daniels. I first encountered him via lectures on various aspects of American history. (Links to them below the video.)

This video is a presentation he did in 2010 on the morality of the free market at TEDxGreenvile.

Lectures by Dr. Eric Daniels:

History of the Supreme Court (Part 1): The Least Dangerous Branch?
History of the Supreme Court (Part 2): Laissez-Faire Constitutionalism?
Property Rights in American History
The History of America – Part 1: Prelude to the Revolution, 1607-1763
The History of America – Part 2 : Making a New Republic, 1763 – 1836
The History of America – Part 3: Expanding and Securing the Union, 1836-1877 
The History of America – Part 4: The Industrial Republic, 1877-1920
The History of America – Part 5: Modern America, 1920-1975
Vanderbilt and American Free Enterprise