Probably related: What does Myers-Briggs Type Indicator tell about a person? (LINK)
I know a few people who are quite "into" the Enneagram (website), including some family members of mine. I was sent a book on it recently from some of them. It's a personality analysis/self-knowledge type of system that has supposed benefits. From their FAQ (LINK):
What is the Enneagram?
Don Riso has defined the Enneagram as "a geometric figure that delineates the nine basic personality types of human nature and their complex interrelationships."
What use is the Enneagram? How can it help me?
The Enneagram can be extremely useful to everyone as a source of self-knowledge because it acts as a kind of "mirror" to reveal features of our personality that normally are invisible to us. Most of the time, people function habitually, as if on "automatic pilot," according to the pattern of their basic personality type. Usually this allows people to get along well enough in their lives, but when their normal routines break down or the stresses of their lives increase too much, their normal way of coping also tends to break down or become dysfunctional. Seeing clearly what our habitual patterns are—seeing what we are doing and why we are doing it, and at what cost to ourselves and others—holds the key to our liberation. By knowing your type correctly, you are able to see yourself—to "catch yourself in the act"—as you move throughout the day. With this increased self-awareness, you are also able to avoid reacting in negative and potentially dangerous ways.
So, is there any evidence to support the Enneagram, its method, its potential beneficial effects on the individual if understood/studied, etc.?