I am obsessed with this book. I'm not a hippy, I just find this kind of thing fascinating. Don't be fooled by the terribly cheesey title & cover; it is a fascinating numerology system that has Pythagorean lineage and appears to be scarily accurate.
It's unlike your typical horoscope-esque guide etc., it covers every possible number combination of the 20th century and gives a detailed 4-5 page break down for each of those combinations. The book is very easy to read, with an introduction to the system, a chapter on each key number and some additional information that is of interest. It's clear and straight to the point.
What I liked about this system of numerology that Dan Millman presents, is that it doesn't define your personality as many other systems of this sort do. Rather, it addresses the central things that you will deal with in your life, which may be reflected either positively or negatively (and not indefinitely positively or negatively either, but differently in different situations, for example).
I am now a creep who asks people their birth dates within minutes of meeting them. Not to say I absolutely sincerely put all of my faith in this system - I just, as I have said, find it incredibly fascinating. In the way that someone is fascinated by and acts according to superstition, without necessarily truly believing absolutely in it. I do however find that it reflects accurately and relevantly in my life; and I do encourage people to look into it if it is something that is of interest to them.