The only two i've ever meet were Dio, he was doing an in store autograph session back in 1998 and Brian Fair from Shadows Fall earlier this year. I just exchanged brief pleantries with them and told them I like their music but both were very cool. The meeting with Brian Fair was just a chance encounter though. They were on a tour supporting 5FDP and he was just hanging out at the bar after the show so I just went up and meet him which a lot of people were doing.
I don't go out of my way to meet too many band members because if they're dicks it can ruin the image of them you built up for yourself and can also affect how you end up liking their music.
3/20 - Dream Theater