Most of the books already mentioned are required to graduate high school. OK
Teachings Of Don Juan - Carlos Castaneda - good book about tripping out with a native shaman.
Tropic Of Cancer - Henry Miller - One of the best cult novels ever.
Cry Of The People - Will show you what really goes on in Latin America due to US policies.
Peoples History of The USA - Zinn - Will show you what we really did to get were we are as a country.
Ficciones - Jorge Borges - Dont really know how to explain this one, but good book.
Junky, Naked Lunch, or pretty much anything by William S. Burroughs

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