The Enneagram is an amazing tool - folklore suggests that it originates in one of the mystic sects of ancient Sufiism, the esoteric part of Islam, but it has no religious overtones.
Read up on Wikipedia's definition: http://en.wikipedia.org/wiki/Enneagram
I've studied the Enneagram for over 15 years, and I can't say enough about it. It has not only provided an excellent tool for my interpersonal relationships, but has been applied directly to my client and business relationships too.
This event would provide an excellent introduction - a taste so-to-speak - from which you can then delve further.
Type the word "enneagram" into Amazon.com's search and close to 1000 results come up.
I'll have to check out the book Sterling mentioned above. Here's two on my bookshelf at home: The Wisdom of the Enneagram
And this one - a fantastic introduction with easy-to-read with cartoon-like illustrations, that I've recommended time and time again over the years: The Enneagram Made Easy

