Adventures of Jonathan Gullible
A 'Free Market Odyssey' presenting philosophical legacy of liberty and principles of free market economics in a simple form.
http://jonathangullible.com/

Libertarianism: A Primer
A guidebook to the libertarian perspective, detailing its roots, central tenets, solutions to contemporary policy dilemmas, and future in American politics, written by Cato Executive Vice President David Boaz.
http://www.libertarianism.org/

Why Freedom
Jason Junge's book, includes links, articles, and editorials on freedom.
http://whyfreedom.com/