I'd recommend the following; I think I'd be doing the books I recommend a disservice if I tried to use my own words to sum them up, so I've stolen little summaries/synopsis from elsewhere.
Animal Farm by George Orwell is a pretty good, fast read.
The plot is an allegory in which the pigs in a farm play the role of the Bolshevik revolutionaries and overthrow and oust the human owners of the farm, setting it up as a commune in which, at first, all animals are equal.
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The End of Poverty - Economic Possibilities for our Time by Jeffrey Sachs
A comprehensive look at the causes of global poverty, and the realistic action that can be taken to half extreme poverty by 2015 and end it by 2025.
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How are We to Live? - Ethics in an Age of Self Interest by Peter Singer
Hard to summarize, I'd quickly check out this wikipedia link if you wanted to know a little about it.
How Are We to Live? - Wikipedia, the free encyclopedia
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The Pig that Wants to be Eaten - and 99 other Thought Experiements by Julian Baggini
To stimulate philosophical thinking, Julian Baggini's The Pig That Wants to Be Eaten proposes no fewer than 100 problems, ranging from Zeno's Paradox and Plato's Cave to cinematic conundrums like Groundhog Day and Minority Report.
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I agree with Netopalis about 1984 by George Orwell and the book Hitchhiker's Guide to the Galaxy by Douglas Adams.
You can find 1984 online if you follow the below link.
Nineteen Eighty Four - Part 1 - Chapter 1 - Book by George Orwell - Charles' George Orwell Links
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God's Debris - A Thought Experiment by Scott Adams:
You can read it from your browser if you follow the below link.
G o d ’ s D e b r i s - Scott Adams
"It's a controversial book that presents a philosophically strange view of the universe. According to Adams, it splits readers between "the best book they've ever read" and "an insult to literature and a disservice to humanity"." - Plutor
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The Outsider by Albert Camus is good. (More specifically the Gilbert translation of L’Étranger.)
Meursault is a young man who works as a clerk in Algiers. He lives in the usual manner of a French-Algerian, middle-class bachelor, cooking his evening meal for himself in his small flat, sleeping with his girl at the weekends, bathing, going to the pictures. But he has a glaring fault in the eyes of society-- he seems to lack the basic emotions and reactions (including hypocrisy) that are required of him. He observes the facts of life, death, and sex from the outside. Even when he is involved in a personal tragedy which results in a frightening and unjust trial, he considers his own feelings and the actions of others with a calm and almost ironic truthfulness.