I had the luxury of seeing John Williams last year in San Diego for a benefit concert. I actually bumped into him as he was going to the elevator and didn't realize who it was until I turned around. He's pretty tall in person!
He did a cool composing demonstration with the opening to The Last Crusade. He showed the entire scene (from Young Indy taking the Cross until he escapes the train through the magic box) without music, and then after they played it again with the orchestra doing the soundtrack LIVE!
He also did Star Wars, Harry Potter, Superman, the Raiders March, Schindler's List and Jurrasic Park.