I met Nicko McBrain (Iron Maiden) at a McDonalds many years ago. A few minutes later Kerry King and I think it was Paul Bostaph at that time walked in. Didnt go up to them though but got Nickos autograph.
When I played at a Norwegian Festival a couple of years ago I met and spoke to most of Arcturus. Their lead guitarist was really nice as was Hellhammer.
I met Dave Mustaine and the rest of the band backstage on the "system has failed" tour.
Then I've met many pro-wrestlers. Basically the whole SmackDown roster as it was in 2003 or 2004 (inluding Chris Benoit, Eddie Guerrero, Big Show, John Cena and The Undertaker). Met em all at the hotel they were staying. Me and a few friends were sitting right next to them for most of the night.
I have also met japanese wrestlers. Most notably the legends Mitsuharu Misawa and Kenta Kobashi. Allthough this was at a autograph signing which probably doesnt really count. If it counts I've met a few more famous people as well.
I've found that Im almost never star struck though. I guess Im just to calm of a guy...