I'm feverishly working on a "short paper" for my first semester in Goddard's MFA program. Since personality typing systems have intrigued me for years, I decided to focus on using one in writing.
I chose the Enneagram, a nine point system which includes many different levels of health and integration because of it's dynamic nature. Not only can an author use the Enneagram to create a character, the flexibility built into the Enneagram allows an author to track a consistent arc of character development.
As with most of my brilliant ideas, I found that somebody else had "my" brainstorm first! There's even software available. To learn more, check out Judith Searle's book, The Literary Enneagram: Characters from the Inside Out, and Character Pro 5. Software. Searle provides a short essay on the nine personality types and examples of characters, actors and their Enneagram types at writersstore.com.