Someone asked me to put together a reading list (I'm flattered... I'm sure other peoples' reading lists would be much more useful than mine). But for posterity, these are books I feel have been tremendously instrumental in my development as a thinker through the end of college. They're in no particular order and vary from ethical philosophy to political thought to economics to literature to investing.
Plato: Complete works, but particularly
Euthyphro, Phaedo, Meno, Apology, Crito, Symposium, The Republic
All of them are fast reads except the Republic, which is basically the foundation of much of how we view political philosophy. The first 6 are tremendous examples of how logic works. Certainly many of the conclusions are absurd, and I find the subject matter of Symposium to be jarring to my modern tastes, but they shaped my understanding of reasoning, cause and effect and counterargument. Best thing to do with these is to analyze the argument, and come up with problems. Then come up with problems with your problems, and keep going til you can't do any more. Then read on and see how Plato deals with them, and repeat. The Republic is extremely interesting as a political work and shows where a lot of what we believe in comes from.
Machiavelli: The Prince and Discourses on Titus Livy
The Prince is an introduction to political strategy, and Titus Livy is the first book I've ever read that proposes a more constructive republic based on incentives for leaders and the people. It's important to remember who each of the books were written for before criticizing the ruthlessness of The Prince too harshly (The Prince is supposed to support the notion of empire because it's written for a prince, while Discourses on Titus Livy shows how to construct a good republic).
Hamilton/Madison/Jay: The Federalist Papers
The ultimate introduction to how our government is supposed to work, as envisioned by the founding fathers. An absolute masterpiece.
De Tocqueville: Democracy in America
Another masterpiece, this time on what makes democracy work and what makes it stop working. Unbelievably prescient about both good and bad aspects of our society 200 years later.
The Bible shapes so many arguments in ways that aren't entirely clear without reading it that I would assert it's a necessity to be educated to read it from a critical point of view. It's also a pretty cool work when examined as literature. (I should probably read the Koran, as well)
Victor Hugo: Les Miserables
The French Shakespeare, he illuminates the devastations of poverty, the potentially positive power of religion in society, and questions what it means to be an honorable person. His prose is by far the most beautiful of any prose I've ever read.
Brilliant. Absolutely amazing - powerful speeches, powerful concepts, amazing use and invention of the English language. I would recommend reading "The Elizabethan World Picture" by Tillyard first - it's very, very dry, but you will enjoy Shakespeare infinitely more. My personal favorites are Henry IV part II, Henry V and Macbeth, though the Merchant of Venice, Hamlet, Lear, Tempest and Winter's Tale are interesting, as well. Everything (except maybe Merry Wives of Windsor) is worth reading for SOMETHING though.
Dostoevsky: The Brothers Karamazov
Beautiful prose, more interesting religious vs intellectual themes, and one particularly beautiful chapter called "The Grand Inquisitor."
JS Mill: Utilitarianism
Utilitarianism has plenty of problems, but it's certainly an interesting way to think about things.
Warren Buffett: Berkshire Hathaway Shareholder Letters
The man is brilliant. Ignore the Berkshire specific observations, if you want (I learned a lot from them)... the man is one of the most common-sense economists, psychologists and financiers I've ever seen. Does a better job examining mass psychology than almost anyone else I've read.
Mankiw: Principles of Economics
Economics is an exceedingly useful topic, even if you have no interest in anything to do with money.
Any solid introductory statistics or econometrics textbook
Numbers can be manipulated in a million different ways. Understanding how these work is imperative to good analysis.
Faulkner: The Sound and the Fury
PHENOMENAL. 1/4 written from the perspective of a mentally-challenged person with no conception of the notion that time moves linearly, 1/4 from the perspective of an insane person about to commit suicide, 1/4 from a cynical sociopath and the final 1/4 from an omniscient narrator on Easter. You can see why this is brilliant.
RL Stevenson: Treasure Island
Just plain entertaining
Michael Porter: Competitive Strategy
As a confession, I've never read this book cover to cover. It's too dry. But I've excerpted a significant amount of the book and it's extremely useful in understanding the dynamics of capitalism.
Philip Arthur Fisher: Common Stocks, Uncommon Profits
Fisher was the original growth investor, who also happened to be one of the first to connect competitive advantage with long term sustainable growth. His book is very investment focused, but the reason I think it's cool is that it expounds on the types of conditions we should want to foster in American entrepreneurs as a whole to help create sustainable growth for America. If you're not interested in the investment conclusions, it still has lots of policy implications.
If I think of others, I'll post them.
For blogs, I also strongly recommend Greg Mankiw's and Tyler Cowen's Economics blogs. They tend to be done pretty well.