Myers Briggs. We took the tests, confirmed our types, and talked about what that meant. I'm an INFJ - someone who needs to recharge her batteries alone, lives in the abstract, places a priority on feelings and subjective decisions, and is highly comfortable with schedules and programs. What about you?
Aside from the personal and relationship value (like understanding why my husband forgets to shave or immediately jumps into picking apart a news article I thought was "neat"), I found the exercises also useful for my writing. What personality types are my characters? I think my most recent character is an ENFP - she's definitely into the abstract, and does not need to have things planned out. In fact, being willing to fly by the seat of her pants gets her in considerable trouble, when she follows someone else's lead into a very dangerous situation. I like the idea of using this framework in my writing in the future, particularly for helping me understand the conflict between my characters. I know folks out there use character worksheets - what are some of the other tools you use?