Carl Gustav Jung (Psychologist and "Pseudo-Science" philosopher whose insights into dreams and the psyche of man are incredibly profound...plus he smoked the greens!)
Michel de Montaigne (saw him mentioned :thumbsup
and
Alan Watts (western philosopher who entrenched himself in eastern philosophy i.e. Buddhism, Hinduism, Tao etc. and deals a lot with consciousness and existence. Highly recommended!!!)
Terrence McKenna (the king of psychedelics, consciousness and reality)