Most famous person I've ever met would have to be Robin Williams, in an EB Games store in Winnipeg, MB. He was on a movie shoot (The Big White), and buying video games at the time (Battlefield 1942). Got to shake his hand, it was pretty cool.
Also met Khari Jones, who was at the time the starting quarterback for my beloved Winnipeg Blue Bombers (CFL Football) in an airport waiting lounge.
My best story, though: the Bible college I attended invited Stockwell Day, former Leader of the Opposition in the Canadian Parliament, and currently Minister of International Trade, to speak in chapel one morning. I met and chatted with him a bit, in the Men's room before chapel started. Just one of those weird random stories.