I always loved reading about space growing up, and I read everything from sci-fi to real stories. One of my favorites was Carrying the Fire: An Astronauts Journey by Michael Collins (the third Apollo 11 astronaut), which I read in Swedish translation (as I was just 7 or 8 years old at the time).
So when Neil Armstrong stepped up on stage at the 2007 Lotusphere Opening General Session, that was the coolest speaker ever. And he was not just another celebrity, he was interesting and funny. My favorite quote was this (as far as I rememeber):
The scientists came up with an experiment to measure the distance from Earth to the moon, using a laser. But in order to do that, they needed a mirror placed on the lunar surface. I was the service technician tasked to put the mirror there.
Best speaker ever, and with Lotusphere being renamed to Connect, he will keep that title forever.