I knew that one of my kouhai in the dojo and I shared a birthdate. And I knew that the Princess (at work) and I share a birthdate. I have another friend who every year sends me e-mail reading "they say it's your birthday/well it's my birthday too" because we share a birthdate. But I just got told that I happen to share a birthdate with the uber-good, really sweet 10th degree grand master who came over to America to teach a seminar for us last July. I am perversely pleased.
(Oh yeah, and the probable future empress of Japan was also born on my birthdate. It was a very good day to be born.)