I am currently reading Keith Haring: Journals, it is amazing and inspiring. Keith got so much done in his short life and changed so much about the art world. One of his journal entries (I'm not sure what he is responding to), "I don't believe art is propaganda; it should be something that liberates the soul, provokes the imagination and encourages people to go further. It celebrates humanity instead of manipulating it."
I have also highly recommend David Wojnarowicz, Waterfront Journals.
What do you recommend?