I was in Hawaii for a high school trip back in 2003, and we saw Tia and Tamara Mowry (the Sister, Sister twins) walking with a friend (not famous) on the other side of the street. There was a group of us, and being dumb high school kids, we basically just yelled "TIA AND TAMARA!" and ran across the street to talk to them. They were very nice, and probably had every reason to not be. After a few minutes, their not-famous friend said "OK, we have to go" and basically dragged the two of them away. That's probably why she was there. Either way, I've always had a lot of respect for them not being short with us.
I also met Ron Darling 8ish years ago, he was one of the speakers at a breakfast event in Long Wharf, talking about the epic game he pitched against Frank Viola in college. I got to meet him and tell him I was a big fan. It was a small gathering, because of a snowstorm, but there were enough people there that wanted to talk to him so I didn't talk his ear off. At one point during a lull, he struck up conversation with me, since I made it clear that I was a big Mets fan. He told me not to get too discouraged, that he thought that the team had a chance with the young pitching coming up to be pretty good soon. He was right -- I'm pretty sure the next season is when Matt Harvey debuted, and they made the World Series 3 years later.