i can't believe no one has said Be Here Now by Baba Ram Das
other than that, to the person who was wondering about the JD Salinger novel, I think that the book your friend was referring too was Franny and Zooey , which is an excellent novel.
The Power of Myth by Joseph Campbell is good, hell anything by Joseph Campbell is...
of course pump your veins full of Kerouac, Burroughs, Bukowski, Ginsberg, and all the beats...
Memories, Dreams, Reflections by Carl Jung is intense for those of you who enjoy psychology
Journey to the East by Herman Hesse
The Man Who Mistook His Wife for A Hat by Oliver Sacks is great for those of you who are into reading about freaky brain injuries
and just for good measure Tuck Everlasting by Natalie Babbitt is one of the best children's books ever.
there's many more i could list but yeah, i'll leave you with that.