Which way is the dancer twirling? Clockwise or counter clockwise?
If she's moving counter clockwise, you are left brain dominant. If she's moving clockwise, you are right brain dominant.
Click through here is a list of the differences in the cognitive styles. Also, here's a small list of right vs. left characteristics.
For the record, I cannot get the dancer to twirl counter clockwise, suggesting that I'm right brained. I'm big on patterns, have disregard for authority or ranking, am free with feelings, and am spontaneous. But I am no good at manipulating objects (the only people worse at parallel parking then me don't bother, which makes me, officially, the least capable person to actually still try), something I'd supposedly be good at if I were right brained. And I do prefer talking and writing, which should make me left brain. But in spite of all that, the dancer only moves clockwise for me.
[And thanks, Jordan, for another intriguing bit of cognitive science trivia.]