Most of my anecdotes involve celebrities I've met at various conventions in one way or another. One of my favourites is from Toronto's Pride weekend in 2007. I was waiting for a bus after the bars let out, around 3:30 in the morning, when the other guy at the stop started a conversation:
Him: Are you coming to the parade on Sunday?
Me: I can't, unfortunately. I have a meeting.
Him: What kind of meeting?
Me: I work on a science fiction convention, and our last committee meeting before this year's convention is on Sunday.
Him (imagine this all in one breath): Oh-my-god-you-work-on-science-fiction-conventions?-Did-you-know-Ellen-Muth-from-Dead-Like-Me-was-here-for-one-of-those-last-year-and-I-wanted-to-go-but-I-couldn't-get-the-time-off-work-and-I-was-so-upset-because-I'm-her-biggest-fan-ever!
Me: Um... yes, I did. I actually ran that convention.
Him:

*speechless, puts his hands up to his mouth*
We had our first date about a week later. About two months later, I was in Atlanta for Dragon*Con, and Ellen happened to be there. She didn't have anyone lined up at her table when I walked by, so she waved and called me over. We chatted for a few minutes, and I told her about the young man I'd been seeing and how he was a big fan of hers. I said, "I wouldn't normally ask this kind of thing, but I'm not holding anyone else up who wants your autograph. Feel free to say 'no'... if I called him in Toronto right now, would you say hello?" She said, "I'd be happy to!" So I dialed his number, but it went to his voicemail. So she left him a two or three minute message.
About an hour later, he called: "Oh-my-god-how-did-you-manage-to-get-her-to-do-that-thank-you-so-much-I-have-to-figure-out-how-to-save-that-message!!!"
Then, Ellen was a guest at Polaris 22, two summers ago. As the person mostly in charge of booking author guests, I was going to the airport to meet Jim Butcher (the author of the Dresden Files books). Three of us got into the limo to head over to the airport, and the person from the department that handles the actor guests said, "I hope you don't mind, we're picking up one of the actors on this trip too." I said, "Of course I don't mind." She said, "Good, would you mind standing near the exit from Customs with this sign?" and handed me a sign that said "E. Muth".
I was standing near the exit when she came out, saw me, and came right over. The exit from Customs at Pearson Airport is at the top of a ramp, so she looked down at me, smiled, and said, "Hi! Remember me?"
Later that weekend I found out she'd been watching the video footage of previous conventions that we air on the in-house TV system in the hotel, because we were walking through the back hallways of the hotel - she was on her way to her autograph session, and I was escorting Jim Butcher backstage - and she said, "I saw you on TV this morning!" I felt like saying, "Shouldn't I be saying that to you?"
Not nearly as cool, but still kind of cool, was the fact that David Hewlett nearly landed in my lap during the Constellation Awards ceremony a few months ago when Michael Hogan threw him off the stage (they'd improv'd a routine where Hewlett ran up to the stage when Hogan was announced as the winner of the category in which they'd both been nominated - Hogan chased him up, grabbed the award from him, manhandled him over to the edge of the stage and threw him off).
Okay, it wasn't that close - he missed me by about ten feet (I stage manage the show from a desk in front of the stage), but it sounds better that way.
