Read:

Siddhartha - http://en.wikipedia.org/wiki/Siddhartha_(novel)

Das Steppenwolf - http://en.wikipedia.org/wiki/Steppenwolf_(novel)

Into the Wild - http://en.wikipedia.org/wiki/Into_the_Wild_(book)

Bought, but yet not read:

Godel, Escher, Bach - http://en.wikipedia.org/wiki/G%C3%B6del,_Escher,_Bach

Being and Nothingness - http://en.wikipedia.org/wiki/Being_and_Nothingness

CODE - http://en.wikipedia.org/wiki/Code:_The_Hidden_Language_of_Computer_Hardware_and_Software

Let´s hear what HN recommends and is currenty reading