
A classic collection of Bertrand Russell's more controversial works, reaffirming his staunch liberal values, Unpopular Essays is one of Russell's most characteristic and self-revealing books. Written to "combat... the growth in Dogmatism", on first publication in 1950 it met with critical acclaim and a wide readership and has since become one of his most accessible and popular books.
Philosophy is science in the circumstances of insufficient knowledge. That is, given insufficient data it may still be beneficial to ponder possible future directions of research, contemplate lines of attack on long-standing questions, or even determine beforehand how these big questions should be posed. All of these circumscientific activities and thinking together constitute philosophy.
Almost everything they wrote, but some good starting points:
Chesterton - Heretics, Varied Types
Hazlitt - The Plain Speaker, Table-Talk
Emerson - Essays: First and Second Series
Stevenson - Virginibus Puerisque, Across the Plains
Santayana - Little Essays ed. Logan Pearsall Smith
Russell - Unpopular Essays, Sceptical Essays
Mencken - Selected Prejudices
Wilde - Intentions
James - Talks to Students, Memories and Studies
I'll recommend Sceptical Essays, Unpopular Essays, and The Conquest of Happiness (all by Bertrand Russell).
Or almost anything by Orwell; his crankiness knows no limits.
If I had to pick just one for you - Voltaire's Bastards.
edit: Also La Rochefoucauld's Maxims should be very high on a list of exposés - it's a savage exposé of oneself. La Bruyere's Characters is a milder but still at-times-scathing exposé of the world. As is Fable of the Bees..
SARK's first 4-5 books, Robert Fulghum's books, Emerson's essays, Hazlitt's essays, Bertrand Russell's essays (e.g. Sceptical Essays, Unpopular Essays), GK Chesterton's essays and his book Heretics, Nietzsche's books, William James' essays, RL Stevenson's essays, La Rochefoucauld's Maxims, La Bruyere's Characters, Kurt Vonnegut's The Sirens of Titan, Ben Zander's The Art of Possibility...