These audio books are from my favorite Free audio book site, LibriVox. This is pretty much their entire Philosophy archive, although there are works always in progress that will appear on their site at a later date. The following links are direct links to download the book, thus circumventing unnecessary page surfing and searching through a huge index of material non-related to philosophy. I Love these books, I have them uploaded in my iPod and listen to them at work. This list contains both friendly and hostile works. It's good to understand the premises of the opposition, especially if you're in an argument with one.

All recordings are in the "Public Domain" and are recorded by volunteers worldwide. You yourself can volunteer if you like. I thought about it myself and I may.

Here is a link to the entire catalog:
Audio Books

Philosophy Archive:
The Theory of Social Revolutions, by Brooks Adams
Poetics, by Aristotle
Politics, by Aristotle
The Essay's of Francis Bacon, by Francis Bacon
Offences Against One’s Self: Paederasty, by Jeremy Bentham
A Treatise Concerning the Principles of Human Knowledge, Part 1, by George Berkley
The Consolation of Philosophy, by Boethius
Discourse on Method, by René Descartes
Meditations on First Philosophy, by René Descartes
The Enchiridion, by Epictetus
The Golden Sayings of Epictetus, by Epictetus
The Praise of Folly, by Desiderius Erasmus
Leviathan, Books I & II, by Thomas Hobbes
Leviathan, Books III & IV, by Thomas Hobbes
Dialogues Concerning Natural Religion, by David Hume
An Enquiry Concerning Human Understanding, by David Hume
Essays in Radical Empiricism, by William James
The Moral Equivalent of War, by William James
The Critique of Pure Reason, by Emmanuel Kant
The Critique of Practical Reason, by Emmanuel Kant
On the Popular Judgment: That may be Right in Theory, but does not Hold Good in the Praxis, by Emmanuel Kant
Perpetual Peace: A Philosophic Essay, by Emmanuel Kant
Two Tactics of Social-Democracy in the Democratic Revolution, by Vladimir Lenin
Two Treatises of Civil Government, by John Locke
A Letter Concerning Toleration, by John Locke
Meditations, by Marcus Aurelius
Das Capital, Vol. 1, by Karl Marx
The Communist Manifesto, by Karl Marx
Essays on Some Unsettled Questions of Political Economy, by John Stuart Mill
On Liberty, by John Stuart Mill
The Subjection of Women, by John Stuart Mill
Utilitarianism, by John Stuart Mill
The Antichrist, by Friedrich Nietzsche
Beyond Good and Evil, by Friedrich Nietzsche
The Twilight of the Idols, by Friedrich Nietzsche
Thus Spoke Zarathustra, by Friedrich Nietzsche
Common Sense, by Thomas Paine
The Republic, by Plato
The Apology of Socrates, by Plato
Euthyphro, by Plato
Ion, by Plato
Unto this Last: Four Essays on the First Principles of Political Economy, by John Ruskin
The Problems of Philosophy, by Bertrand Russell
Studies in Pessimism, by Arthur Schopenhauer
The Wealth of Nations, Book 1, by Adam Smith
The Wealth of Nations, Books 2 and 3, by Adam Smith
The Philosophy of Style, by Herbert Spencer
On the Duty of Civil Disobedience, by Henry David Thoreau
The Art of War, by Sun Tzu