Here are several “entry-level” books that are also available in audio format and can be read or listened to in a few hours each.
The Revolution: A Manifesto [Audible] by Dr. Ron Paul. This a good place to jump-start fresh thinking on a variety of topics: war, economics, money and banking, constitutions, education, environment, healthcare, and more.
An accessible, timely book about the current financial crisis I would recommend is Meltdown: A Free Market Look at Why the Stock Market Collapsed, the Economy Tanked, and Government Bailouts Will Make Things Worse [Audible] by Thomas E. Woods, Jr. It includes a nice blend of current-event analysis and solid economic theory.
The Politically Incorrect Guide to American History [Audible] by Thomas E. Woods Jr. This is relevant not only to Americans. Misleading versions of key American historical episodes are often used in schools around the world to teach fundamental narratives, often distorted ones, about the nature and history of government, business, and wars.