Hmm, well maybe biographies of people like Peter Green, maybe Syd Barrett, or the chap from the 13th floor elevators..Roky Neilsen or someone...
A book I'd love to get hold of but isn't easy to find is "The Artistry of the Mentally Ill", a study done by a German psychologist in the 20s or something about the paintings of some schizophrenics. Sounds amazing.