I've had a few of these:

When I was in 4th grade I was living in North Carolina. One of my friends from school moved away. I wasn't sure where. Two years later my family moved to Florida. My first day in my new school, out on the playground during recess, guess who I see??

I have a very unusual last name. There's probably less than a thousand of us in the country. Any how, I spent the first 9 years of my life in Chelmsford Mass. 15 or so years later I'm in California, getting high with my boss when he introduces me to an old friend of his. When my boss tells him my name he says "You're not the same Michael P. ____ that lived in Chelmsford Mass, are you?" I nearly shit my pants. Turns out he had the same last name and just happened to live in Chelmsford too. He had always looked in the phonebooks for other people with our last name and mine(actually my Father's-I'm a Jr.) was the only one he had ever found. Turns out we're probably distant cousins.

I spent a semester studying Mandarin in Shanghai China. My roomate at the time was also from the U.S. after our semesetr we both came back to the U.S. A year later I returned to Shanghai to continue my studying and to work as an English teacher for a year. One rainy afternoon, in a part of the city far away from the school where I just randomly wandered into, I'm walking down the street when I look up and see my old room mate walking down the street. Now keep in mind that Shanghai has about 14 million people. The odds of just running into anybody are pretty slim.

I figure the odds of any of these happening are pretty astronomical. But 3 times?? Unfortunately I still can't seem to win the lottery