In the early '80's I was on a Pan Am flight from NY to PGH and was invited up to the cockpit during takeoff. I was allowed to sit in front of the pilot and help pull up on the u shaped thing (ok, maybe it's the throttle, how the heck do I know)
Post 9-11 we were allowed to visit the cockpit of a UA flight (Nov '01) from IAD with my 1 yr old pre departure. Photo op was really neat and one of my favorite family pics.